• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Introduction
 Fly larval migration from...
 Control of blow flies
 Density and seasonal fluctuations...
 House fly breeding in compost
 Migration and dispersal
 Summary, conclusions and recom...
 Appendix
 Literature cited
 Biographical sketch






Title: Ecology and control of the principal flies associated with a compost plant /
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Permanent Link: http://ufdc.ufl.edu/UF00097655/00001
 Material Information
Title: Ecology and control of the principal flies associated with a compost plant /
Physical Description: 121 leaves : ill. ; 28 cm.
Language: English
Creator: Alvarez, Calvin Gale, 1943-
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1971
Copyright Date: 1971
 Subjects
Subject: Flies -- Control   ( lcsh )
Entomology and Nematology thesis Ph. D
Dissertations, Academic -- Entomology and Nematology -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (Ph. D.)--University of Florida, 1971.
Bibliography: Includes bibliographical references (leaves 115-120).
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita.
Statement of Responsibility: by Calvin Gale Alvarez.
 Record Information
Bibliographic ID: UF00097655
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000430658
oclc - 37639609
notis - ACJ0008

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Table of Contents
    Title Page
        Page i
        Page i-a
    Acknowledgement
        Page ii
        Page iii
    Table of Contents
        Page iv
        Page v
    List of Tables
        Page vi
        Page vii
    List of Figures
        Page viii
        Page ix
    Abstract
        Page x
        Page xi
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 7a
        Page 7b
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
    Fly larval migration from refuse
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
    Control of blow flies
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
    Density and seasonal fluctuations of house flies at the compost plant
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
    House fly breeding in compost
        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
    Migration and dispersal
        Page 72
        Page 73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
        Page 93
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
        Page 99
    Summary, conclusions and recommendations
        Page 100
        Page 101
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
    Appendix
        Page 107
        Page 108
        Page 109
        Page 110
        Page 111
        Page 112
        Page 113
        Page 114
    Literature cited
        Page 115
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
    Biographical sketch
        Page 121
        Page 122
        Page 123
Full Text









Ecology and Control of the Principal Flies
Associated with a Compost Plant











By

CALVIN GALE ALVAREZ


A DISSERTATI'N PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY








UNIVERSITY OF FLORIDA
1971




































Uti,.'ERSiT OF FLORIDA
31 1262 08552 47821 1 11 1
3 1262 08552 4782













AC KIOWLEDGMENTS


The author wishes to extend his sincere thanks and gratitude to the

many persons who have made this endeavor possible:

To Dr. F. S. Blanton and Dr. H. D. Putnam for serving as co-chairmen

of the supervisory committee, and their assistance and friendship through-

out this investigation.

To.Dr. G. C. LaBrecque for serving as a committee member, for his

assistance, direction, and friendship, and for providing equipment and

working space at the United States Department of Agriculture's Insects

Affecting Man and Animals Laboratory, Gainesville, Florida.

To Dr. J. F. Butler for his participation with the committee, for

providing equipment and working space at the Medical Entomology Laboratory,

and for his tolerance of the odors of rearing blow flies.

To Dr. D. H. Habeck for his assistance and work with the committee.

To Dr. W. G. Eden for his guidance, encouragement, and assistance.

To Dr. D. L. Bailey for providing equipment and advice.

To Dr. D. E. Weidhass and all the other members of the Insects

Affecting Man and Animals Laboratory for providing counsel and aid on

many occasions.

To Mr. Dan Wojcik and Mr. Terry Marable for photographic assistance.

To the Department of Environmental Engineering of the University

of Florida for financial assistance provided by Contract number 5-701-UI-

01029-09 from the United States Public Health Service.









To Mr. Herb Houston, project director of the Cainesville Municipal

Waste Conversion Authority, :r.c., and Dr. D. T. Knuth, Environrmer.:al

Engineering, Inc., for furn sh> n; eqjiT.D.-t ar.d faci i:!es as provided

by Department of Hea!lh, Educa:ion, and welfare e De-or.strat:cn Grar.t

number 5-D01-U1-00030-02.

Finally,, the author wishes to express his deepest gratitude to

his wife, Judi, for her patience and constant enccuragemert during this

stuay.














TABLE OF CONTENTS
Page

ACKNOWLEDGMENTS .................................................. i

LIST OF TABLES.................................................. vi

LIST OF FIGURES................................................ viii

ABSTRACT........................................................ x

INTRODUCTION................................................. 1
Statement of the Problem............................ 3
Location of Compost Plant.......................... 4
Operation of Compost Plant......................... 5
Flies .................................... ........... 9

SECTION

I. FLY LARVAL MIGRATION FROM REFUSE......................... 13
Methods............................................. 15
Result and Discussion .............................. 17

II. CONTROL OF BLOW FLIES.................................... 26
Blo.w Fly Traps...................................... 26
Field Tests........................................ 29
Rearing Blow Fl ies.................. ............... 37
Laboratory Screening of Insecticides for
Control of P. cuprina........................... 41

III. DENSITY AND SEASONAL FLUCTUATIONS OF HOUSE FLIES AT
THE COMPOST PLANT ...................................... 46
Rearing House Flies............... .... ..... ....... 46
Seasonal Fluctuations of House Flies............... 47
Evaluation of Fly Sticky Tapes..................... 54
Determination of the Magnitude of the House Fly
Population...................................... 57

IV. HOUSE FLY BREEDING IN COMPOST............................ 60
Moisture and Age of Compost........................ 60
Sludge and Grinding. ................................ 64
Temperature ................... ..................... 67







TABLE OF CONTENTS (Continued)
Page
SECTION

V. MIGRATION AND DISPERSAL ....................... .......... 72
Literature Review ..................... ............ 72
Flight M ills....................................... 75
Bl1~ Flies Released at Compost Plant............... 78
Fly Releases at the City Landfill.................. 81

SUMMARY, CONCLUSIONS AND RECOMM;ENDATIONS....................... 100

APPENDIX

1. Test for the precision of the counting technique used to
determine total number of larvae collected under
the apron conveyor................................. 108

2. Fly larvae trapped under apron conveyor during 1969, at
the Gainesville coTpost plant....................... 109

3. Percent mortality of 5-day old Phaenicia cuprina
females 24 hr after exposure to insecticides
in a wind tunnel .................................. Ill

4. Temperature in digesters ................................... 114

LITERATURE CITED................................................ 115















LIST OF TABLES


Page
TABLE

1. Percent abundance of species of fly larvae trapped
under apron conveyor during 1969................... 19

2. Total number of larvae collected under apron conveyor
compared to number of larvae trapped the same day.. 20

3. Total number of larvae collected per day under apron
conveyor compared to the number caught in the
same area during the night......................... 22

4. Sex, species, and abundance (%) of flies caught in
cone traps baited with I-day old fish heads
at Gainesville compost plant....................... 29

5. Number of flies caught per day in cone traps baited
with fish heads as a monitor of procedures to
control adult flies at the Gainesville compost
plant.............................................. 30

6. Sex, species, and abundance (%) of flies caught by
sweep net in grass adjacent to receiving area
of Gainesville compost plant........................ 34

7. Analysis of several rearing media to determine the most
suitable method of rearing Phaenicia cuprina....... 39

8. LC50 of 5-day old Phaenicia cuprina females to
insecticides in a wind tunnel ...................... 43

9. Air temperatures recorded 15 cm above compost in
digesters at Gainesville compost plant ...... ..... 51

10. Number of adult house flies caught on sticky tapes in
different ages of compost....................... ... 53

11. Recapture of 3-day old marked laboratory reared house
flies by sticky tapes hung in digesters for 24 hr
following release of flies in the same area at
the Gainesville compost plant during 1969.......... 59








LIST OF TABLES (Continued)
Page
TABLE

12. Influence of moisture and age of compost on maturation
of immature house flies reared in compost.......... 63

13. Influence of moisture on maturation of immature house
flies reared in 3-day old compost................. 65

14. Influence of sludge and grinding of refuse on maturation
of immature house flies reared in compost.......... 66

15. Temperatures observed ir house fly rearing containers.... 69

16. Temperatures observed in 4-day old compost in
digesters.......................................... 71

17. Mean distances fla.n in 24 hr by adult Phaenicia
cuprina attached to an insect flight mill......... 79

18. Distance flaomn until death by adult Phaenicia
cuprina attached to an insect flight mill......... 80

19. Recapture of wild marked flies by sweep net and
baited traps 24 hr after release................... 82

20. Recapture of marked wild flies at Gainesville sanitary
landfill by sweep net after release............... 91

21. Observations of marked wild P. cuprina remaining at
Gainesville landfill after release............... 93

22. Observations of marked wild M. domestic remaining at
Gainesville landfill after release ................ 94

23. Average percentage of flies remaining at city landfill
under different weather conditions................. 95

24. Rainfall recorded at Gainesville Municipal Airport
during release studies at city landfill........... 96

25. Observations of 2-day old marked laboratory reared
Phaenicia cuorina remaining at Gainesville
landfill after release............................ .98















LIST CF FIGURES


FIGURE

1. Floor plan of Gainesville municipal caipos: plant...........

2. Refuse flao plan of Gair.esville coinpost plant............... 7

3. Receiving building filled with refuse....................... 3

4. Sorting conveyor carries refuse to sorting platform..........

5. Composting takes place in concrete digesters................ 1

6. The finished product is discharged zo outdoor storage areas. 1C

7. Fly larvae and pupae unJer receiving hopper................. 4

8. Fly larvae migrating from refuse to pupation s:tes under
wall of receiving ouild r......................... .......... 14

9. lumber of fly larvae caught under apron conveyor per
week at Gainesville compost plant during 1969....... 18

10. Eastern edge of approach ramp........... ............... .... 24

11. Fly larvae aiong base of eastern wall of approach ranp...... 24

12. Cone trap baited with 1-day old fish heads to sample
fly populations at compost plant..................... 28

13. Rear vie.- of receiving building shcx-ing receiving hopper
and pavement behind building.................... .... 23

14. tMean number of adult flies captured per sticky tape per
week during 1969, in digesters at Gainesville
compost plant....................................... 50

15. Number of house flies captured on sticky tapes within
24 hr after release in a large outdoor cage......... 56

16. Position of tia'perature process in house fl' rearir.g
containers.................................... 68


viii








LIST OF FIGURES (Continued)


Page
FIGURE

17. Diagram of insect flight mill............................. 77

18. Fly larvae in animal disposal area of city landfill....... 84

19. P. cuprina roosting on grass tassel at night at city
landfill ........................................... 84

20. Predominantly 1. domestic roosting on weed at night
at city landfill................................... 85

21. Predominantly C. macellaria with some M. domestic
roosting or, dead brush in refuse at night
at city landfill................................... 85





Abstract of Dissertation Presented to the
Graduate Council of the University of Florida in Partial Fulfillment
of the Requirements for the Degree of Doctor of Philosophy


ECOLOGY AND CONTROL 0 T:HE PRINCIPAL FLIES ASSOCIATED
..'ITH A CC,-.POST PLANT


By

Calvin Gale Alvarez

March, 1971


Chairman: Dr. F. S. Elanton
Cc-chairman: Dr. H. D. Putnam
Major Department: En:ztcology and rematology
Minor Department: Environmental Engineering


Seasonal fluctuations of Diptera indigenous to domestic solid.waste

w ere examined at the Gainesville, Florida, municipal compost plant during

1968-1969. Populations of both immature and mature forms were estimated

and the efficiency of chemical and physical control procedures -.as

tested. Adult dispersal studies were conducted during 1970 at tne city

landfill.

The major fly source at the compost plant was found to be from

larvae-infested incoming refuse. The greenbottle blow fly, Phaenicia

cuorina (Shannon), comprised more than 90 percent of the larvae ,-hich

migrated into protected areas where they developed into adults. Approxi-

mately 450,000 adult flies per week were produced during the summer

months. This figure could be reduced by more than 63 percent by pro-

cedural changes and good housekeeping.

The daily application of a dichlorvos sugar bait reduced the number

of flies ry Si., percent -.-:hile a s ngle applicat3or. of d:m-ct.loate reduced

t.ne population by m.or th-n 50 perccr.t: for :.ek. ara..: cn, S rba,-.,

naled, ar.d diazinon 'ere a!so .ffcct ve 4s shc.ar. by laorato.-y tests.







The number of house flies captured on sticky tapes was sho.-.n to

be proportional to the number present in a large outdoor cage. Sticky

tapes were used to sho.. seasonal fluctuations of house flies in the

digester building.

House flies we.e the predcxinar.t insect breeding in cocTmpcs:. They

were l imiad to the top 2.5 cm in the digesters because of t iperature.

The optimum moisture content for hcuse fly breed:rn was 73 perc:-.:. r.c

to 14 percent of the eggs placed in ccnpost at 45-55 percent moisture

(normal operating conditions) developed ?nto pupae. Egg survival to

pupce decreased s gnificantly when placed in refuse after 5-10 days of

ccnpos t i r.g.

P. cuj.:n3 -males flea an average of 19,1.05.4 m and a maximum of

30,137 m when attached to a flight mnll until death. Fe.Tales flea. an

average of 25,235.2 m and a maximum.- of 45,030 n.

\-ild P. cuprina and Nt. comestica were marked and released I mi from

a.landfill and later recaptured at the landfill. An average of 10.17

percent of the wild P. cuDrina ar.d 1.66 percent of wild 1I. domestic

released at the landfilll on days follcaed by 24 hr without rain were

recaptured 24 hr after release. An average of 10.7 percent of the wild

P. cuorina released a: the compost plant were recaptured in the same area

24 hr later. An average of 11.3 percent of laboratory-reared P. cup.-Ina

released at the landfill %ere recaptured 24 hr later. Baited traps

surrounding the landfill recaptured only 2 flies after a total release

of 255,000 flies.















I :.T.U,, ) CT '. 3.


The de.T.ands of our affluent soc:et,, for more Socds c.nd cor.'..-.'-.

it-ms such as r.o deposit and non-rczurr.able materials, reL:'t in .f-.2

ger.rati~n of waste products in gigantic proportions. ,1s tne aff,~r.ce

and the population increase, the per capital and total amount of waste

increase proportion iy. The disposal of these tre.-nendcjs c-.z,~tiies

of wastes has primarily been an urban problem. Since the trend in the

United States "s toward urbanization the problems of refuse disposal

becar-e increasingly more important. This becomes evident when it is

noted that in 1960 the estimated median waste per capital per year in urban

areas was 1,430 pounds. This amounted to 1'80 billion pounds per year

ar.d the cost of collecting and disposing of this refuse was more than

1.5 b:llicn doi!ars (1).

To combat the rising problem of refuse disposal the "Sol id Waste
P
Disposal Act" was enacted in 1965 to support a national program designed

to implement and evaluate more efficient methods of coping with the

sol id waste problems. Under this act the Bureau of Solid WLaste Manage-

mer.t awarded a contract to the Gainesville -,Mnicipal Waste Conversion

Authority for the construction and operation of a refuse conpost:ng

facility. The purpose of this project was to "demonstrate the rel iabil ity,

su iab; ity', tcc.-.c.-r:c fL-s ; :it';, ar, L.L n-ita- and nu tance-rre o0.eretIon

of a rccertly Zc>ve. pi d ;',-.- tL, ;.,:J-.,.2,:c-: canpost,.s sys:ttm for ;he

d :spcsc.: cf r-.F :c'..p C fr.. .. ( ,. CI .








The primary objective cf c o costing is to dispose of refuse by

biological degradation of the organic materials. Modern scientific

cc-posting prccecures W'h;ch are emiplc'ed in municipal disposal sy'ste-:.s

involve the rap:d partial deccmnpos i;icn of orcar.ic matter by the use

of aerobic microorganisms under controlled conditions (1), municipal l

composting is a fairly conmon practice in many European countries. It

is rarely used in the United States because lard for refuse disposal was

available in close proximity to urban centers in the past. Th.

increasing demand for land provided the stimulus for municipalities

to seek a more acceptable form of refuse disposal. As late as .53,

ti.ere was little scientific information available on municipal composting

in the United States. Since then several universities and the United

States Public Health Service conducted studies that have as yet yielded

only a limited amount of practical information. The capital and operating

costs of comwposting are kno.-jn to be higher than most other forrs of

refuse disposal but the specific ecor.nnics involved in municipal co-,-

postir.g :n the United States are practically unknown. The feasibility

of co-iposting must be determined by the major advantage of c-nposting,

the recycling of waste products. The sale of marketable compost and

salvagable goods would reduce the net cost and may result in a profit.

There are 2 general composting processes that appear to be the most

efficient and economical under U.S. conditions. The first is mechanical

digestion, a process in which refuse is sorted, ground, and mechanically

manipulated in order to shorten the bioloc:cal degradation process. The

second method terr.med windrc.-.;ng involves the sorting, grinc:ng, and placing

of refuse in windrc. s allo.in; t.-.e rmateri,! to co.npost naturally. The

compost plant constructed a: Gai.-.csvile used .he mechanical .iqestion

process.








Stte-.ent of the P:oblem


As with other scientific informationn concerning composting in the

U.S., little is knawn concerning insect problems that may arise in this

type of operation. The original purpose of the present investigation was

to search out these problems, determine their magnitude, and suggest

possible solutions. Initial observations revealed that large numbers of

fly larvae entered the compost plant within the refuse. These larvae

seeking a suitable pupation site migrated from the refuse stored in the

refuse receiving building. These insects were aesthetically unpleasant

to the employees as the larvae were often crushed beneath their shoes and

sometimes crawled into the clothing of a resting employee. Many of the

immature insects eventually became adults and further tormented the

employees at the site by their constant presence while others were reputed

to invade the surrounding community. Thus, the primary areas of this

investigation were as follows:

To identify the larvae entering the compost plant with the refuse

and to determine the:r magnitude and seasonal fluctuations.

To search out possible processing procedures which may reduce the

number of larvae migrating into the plant.

To evaluate mechanical and insecticidal control procedures to reduce

the larval populations.

To screen several commercial insecticides for their effectiveness

against the emerging adult flies.

To determine the density and seasonal fluctuations of the adult house

flies at the compost plant.








To determTine the extent and some of the l imiting factors of hcuse

fly, breeding in compost.

To deter-mine the extent of fly c;spersal froT thie coripost pl a-t

;nto the surrour.dr.i cn;To.Tir.. ty.

Laboratoory stude: s ..erc co:.dc:ed at the USDA Insects .".ffect.r.

HMn and Animals Laboratory :n CaIne;v!f e, Fligica, and at the Lnive.:L.ly

of Florida medicall Enom-nology Lcaboratory. F eld s:udeis ccncCc:cea at t.-.c

cornpos plat were begun in June, 13. becausee of a lack o fL.'.cs th .

plant was closed on DecaTmber 31, 1939, ar.d scke cf tae stLcies '..ere not

cxpar._dcd as the author had inte.-.rc, M'.ost cf .~n disperse! s-ud es wrre

aP rform.ed at the C::y of Gainesville SaniZary Lr.-.dfill durinS t'.- s.-.;er

of 1970.



Lc, icn of Cc-.pos: Flant


The compost plant was constructed on a 5-acre tract of land located

ir southeast Gainesville at the city's sewage treatment complex. This

size was near a se.-jage treatment plant, an animal shelter, and an

abandoned dump.

A densely populated region of midd'de-incom.e apartment complexes

inhabited primarily by Universi:y of Florida students and a la.j-incocae

residential area were located in :ne immediate vicinity. A woodland area

buffered a middle- and high-income residential area located one-half

mile from the plant.








C'oeration of CTomost Plant


The floor pl..n c. he cac.post plar.; is p.-csc..ted in Fig. I and tr.c

central flao plan o- ti, r s' .; s .-.n .-. F'.. 2. Fefuse wa. Lro r.. by

trLck andu dLmpcd or. t:.e f:cor of the -eceivir.g .l ldir.g (F:g. ;). re

refuse was then placed n:: a .-ece.:ving hopper by a actortr .o.;fi~; wj. ;

a front-end loader. The hopper ('%.8 r long, 3.6 m wide, -r. 3.i n ec,

constituted the rear side of the building. An apron conveyor which

consisted of a series of ov.erla ppr.; or inter:ockir.g r ron pans %.-s

located at the bottom of th:s hopper. Tne refuse was transported alo-.

the conveyor onto an oscu'lating taZbl. T:.;s ta2.e loosened zne packed

re.use in order to assure c. un:,or. -flo..-. A sor-:ng conveyor car.-ied

the refuse frc., the oscil.ating table to a platform where 6 labo-rrs

manually re .rved salvagemble paper, cardboard, and large bulky items

(Fig. 4). The paper and cardboard were dropped into chutes which fed

into a baler and the bulky teamss were placed in chutes that emptied into

a dump truck which carried these materials to a landfill. Tne sorted

refuse then proceeded directly into a crusher-disintegrator grinding mrill.

The ground refuse discharged froT- the crusher averaged 7.6 cm but varied

in size depending upon the type and amount of material fed into the

machine (20).

Refuse passed frin the first grinder into a second grinding unit which

reduced the particle size to approximately 5 cm It was then discharged

fro- the bottom of the secondary grinder into mixing screws where 2 ccunter-

roating ribbon-cype scre..s, p aced s:de by :ide in a common trough,

blended th. r..a:eria' with wte,- or sludge. A conveyor belt carri-d the

molstcned refuse unctr a rma. tic: separaoe- .- h:ch removed the ferrous







































Ig.r.zr **nrloa blowr
S Illoder m /ealoadl| *bhgCrl* touvyo
giloader creeler car relle
2 I e..r ucloadln co. nyor
Lloader LrecaJr car
e r ld le.dlin convyor
a|riad drcrrlbualg ecrrw conveyor
OlrLOd mll felder ecrer coroveryors(2)
eprlod mille (2)
lalg ad ovar.loa arm roaaeyar
leariad dLschars cvarwr conveyor
Lochplilog belt coaveyor
.toraee buildLng Vorrc c loadLng ramp
.vetorl a*d *r, re
S Ilectricl evitcrner room



1 -"


Fig










































































4TOC.L P II



















































Fig. 1. Floor plan of Gainesville municipal compost plant (20),





















zeCeh.CItI- ,O4PfI


MAN5IIIC 5EPADPL'OI

BUIZN,


pIcuII4 r.bL.5


4TroC- PIL6.


1MAiw MPAN


Fig. 2. Refuse flow plan of Gainesville compost plant (20).





8























Fig. 3. Receiving building filled with refuse.


Fig. 4. Sorting conveyor carries refuse to sorting platform.





9

mTiGtc.,s a...', :;".n 3=t ,-,. o.'.O t .2 ". 2C.C c,'cr.'/Gcyor D '. z o't '-h exc" de.. t

;:a.-.:h of :e d:gestrs. A s.-.ht:.e ccnvey'or, which travelled on a pal- o;

steel rails betwee. the cigeste.-s discharged the refuse into these ur..:s.

T7. disest.- s or c. gst ..g ;ar.,-.s were 2 cc.-.crete rcja, s S9 n c.-.g,

6 m wide, and 2.7 m deep (F:g. 5). The digester walls were constructed of

concrete blocks and the floor was converted with perforated gelvan:zed

stee! plates. These pat:s were above an a.r pier.um into which air was dis-

charged by a centrifLgal 1c.-i pressure fan. River gravel approximately

0.6 crm in diameter covered the perforated plates to a depth of 7-10 -n.

This enabled the air to diffuse evenly through the small slots over the

entire floor of the tank. The refuse was placed in the digesters to a

depth of 1.8-2.4 m and allowed to compost for approximately 6 days (20).

(In t.n:s investigation "crIpost" refers to refuse that has remained in

the c:gesters for a period greater than 24 hours.)

Removal of the compost was accc-.pl ished by a machine called the

Ag:-Loadc.- (Me:ro-.c;ste Patent No. 3,294,451). This machine removed the

cc-post a-.d deposited it back onto the tripper conveyor. A system, of

cc..veyor bets transported the coTnpost to a final grinding mill. A finely

ground mater;ai approximately I cm was discharged froi this grinder and

was transported by conveyor to an outdoor storage area (Fig. 6).



Flies


..ce .mot r~cmerous species o. flies prcsr.: at -:.e c-mpost pla..t were

.hu com.-.cn house fly, Miusca do-est;ca Linnaeus, (.-,scidae, Diptera) and

... r.- .'c.bott e b,. c; fly, -.-: .c cj-..' a ,S. ) (Ca phor-id

Sr..era).































Fig. 5. Composting takes place in concrete digesters.


Fig. 6. The finished product is discharged to outdoor storage areas.







The house fly has beer. incrimin-ated as a carrier of nm.TeroLs diseases

of man and animals incl-ding typhoid fever, cholera, and amroebic dysentary

(27, 2); hc.-.ever, these cla'ns have been supported only by circunstant;:a

evidence. Hacse fly associatiu.-.s ;t;-, disas-s need farther cla-:ficatcon

as cxperimre.r:ta evidence .s sparse and con.tam.iatin of house fl s between.

caged mates has been shao.'n to o sporadic (2-).

Grcenbottle blce f! es may be cc.T.estc nuisances or carry d;seas2

organisms, but in. this coaac:ty ney are far less impc,: r.t: ..-:. other

flies. Hc..ever the damage -nd s-ffe.:r.%g which the Icr-.'ae ir.-I lc Lpo

domTestic animals in sci-e s ock<-.-a s i-o areas .s of tre.-er.dcus co.sequcr.ce.

In Australia, th:s fly is by far the rost important spe:Ies in fi st-ike

or cutaneoJs myas:s of sheep (LL:, 3). ',, strike is a condit:an pro -ced

by the development of blcw f'.l larvae on 1 giving sheep v-.hidh may lead to

death or a considerable loss of woo. This is a formidable problem in

Australia and ar.oun-s to an annual cess of 4,000,000 pounds to sheep

raisers (44, 6$).

The ccr,.on hcjse fly is well established as Musca domestic- Linnaeus

but the systematics of the greer.bottle blo.-j fly are scoTewhat confused.

Australian authors refer to this fly as Lucilia cuorina (v\.'idemann). Hall

(26) cc.mpa;-ed specimens from the United States and Australia and concluded

they were not the same species. He described the A.merican species as a

ne. ccnbinatIon, P. pallcscenes (Shannon). :.laterhouse and Paramo.ov (E0)

later examir.ed numero-s specimens fro-n Texas, Ns. York, 'New.j Orleans,

Washir.gton, and Austral ia ar.d concluded that there was no diiferenc, in

species, bjt a definite pa:r of subspL .- iJmes k2S) ccncLr:'cJ ir. ths

vie.-. .-all later in Sta.; c e al. (7c ma r.ta ,-,ec his cLm.T i ion of







on .cec-z (Sh no) r u reco, -zed the works of Watorhouse and


P -r ammv 7,0, 0u%,o T0scs the species -,z,7, from- Waterhouse and Paramonov

s ince the ir work appeared to be moa- ccr.-orchens ive than that of Hall.















SE-: .C !


FLY LARVA. MIRAT.:C:; FR.m-- REFUSE



The major source of fly infestation appeared to be from I-trodic:ir.

of larvae from. t'e coll ected refuse ar.. not :.-C m br.eca:ng at .:.e c:.,;.;:

plant Fly larvae that .4.ere breed;r.g in refcLe containers thrcj-;ic. :we

city were brought to t.e cC Ts:o p.c-at wiTh the refuse. Th;s infestedd

refuse w.;s stored z.-.'aiting process ..g in : e receiving arca. -an/ .:

the larvae were mature and the a-dc: stir..us of tr.e disruptive transfer

to the p!ant caused them to active/ seek a pupation site (F:gs.7 and 3).

Scne of these larvae migrated :nto the working areas where they' annoyed

the employees while others reached protective areas where they metamorphosed

to adults. Such occurrences v.ere not unique to the compost plant. Large

numbers of larvae may escape to pupation sites during the handling,

transferring, or processing of larvae-infested refuse. G-Cen and Kane (23)

found that 7200 larvae/hr/pcr ca. were escaping from railroad cars a-.aiting

dispatch to a rural disposal area.

The infestation of refuse bI larvae in the Gainesville area uas

anticipated because in a southern California cit, with a climate similar

to that of Gainesvile, Ecke et al. (13) reported that residential refuse

containers can h.v, zs many as C,000 .vae per cc..air,..: over a ]0-we.C

priced. These larvae crcw'.le c c. .? re s .-js c,. sh 't feed:.g period































Fig. 7. Fly larvae and pupae under receiving hopper.


Fig. 8. Fly larvae migrating from refuse to pupation sites under wall
of receiving building.






15

to pupate in the soil and later emerged as adults. During the hot summer

months it was reported that the feeding period was corpleted in 4 days

(79). This observation led to the recommendation and subsequent adoption

of a twice-weekly refuse collection system for several California cities

(17, 79).

The purpose of this investigation was to determine the species of the

larvae escaping into pupation sites at the plant, to determine the

magnitude and the seasonal fluctuations of this massive influx of insects,

and to search out possible processing procedures which would reduce the

total number of escaping insects.



Methods


Seasonal Fluctuations

Visual observations indicated that the majority of the larvae escaping

from the refuse were confined to the partially enclosed area under the

apron conveyor. The larvae reached this area either by crawling through

the openings between the metal pans of the conveyor or by falling through

the opening between the floor of the receiving building and the edge of

the receiving hopper. To determine the species present and the seasonal

fluctuations of the larvae entering the plant, a trap was placed in this

area. This trap was similar in function to the described by Roth (58) and

consisted of a 30.48 cm2 plywood box.. It was abutted to the wall under

the apron conveyor so that larvae falling through the opening between the

hopper and the floor would be trapped in the box. The trap was operated

from January 12 to December 31, 1969.






i

The trap wa:s checked daily and the number of larvae recorded. A

minimum of one sa.-.pl, catch per week was preserved in alcohol for identi-

fication.

PorL nation Factor

It was desired that the lc.-vai population trapped in the se-scnai

fluctuation survey b. used to estimate the total number of la-vae esca?:r.c

into the plant. To accomplish, this .t was necessary t: d.termi..u. ,1

total nL.-.ber of larvae that entered the plant, the percentacg o. t-h

larvae trapped, a.d the re. iab;lity of the trapping p.ocedure.

The tot:l number of larvae enterir.g :-e plant '.;oud be c.. i:L1t

figure to accuratel'y efine. Since the majority of the larvae migrate

under the apror. co..veyor was used tc deter-:ir.e zie total number of

larvae ;n that area and to determine the reliabil;zy.

The larval population under the apron conveyor was determined by

sweepi;.g the area -or a 10-day pe.-od baginnir.c ..ug-st 29, 1909. These

sweepings, which included the debris and .arvae that had fallen during

the p.-evlcus 24 hr, were placed into a 55-gallon (208 1) drum. The drum

ar.d its contents wire weighed, sealed, and thoroughly mixed by rolling

on the floor for several minutes, l..:.ediately a volume of aporoxi.-ately

0.5 1 was removed and weighed on a laborato.-y balance (4aus, Unicn, N.J.).

Tne larvae in the sample wura counted a:,d the total number of larvae in

tne drum or under the aron conveyor was calculated.

To deterr;n.: t.-.e precision of the above method, a sample of approxi-

mately 0.5 1 was .rcmo.'J, I'e'chca, counted, ar.d replaced ir. the drum. The

ccn er .ts cf .,, w..e .ga-; n r.'.xcd' and ..a pr.ced-re wc.s re.;" icated

5 tr:.es. -. .- :..:c c t t :.-. r.ethod was precise and are ;ivtn

in Appr.dA di ..







Effects of Clearina Receiv.inq Bi;ldina Cda'i'. of Refuse

It was standard operating procedure that a sufficient a.mcunt of

refuse remain in the receiving building o.vcrnig.h so that operations

could becin the folllja ing r.crr.t.g and proceed without inte.-ruptior. L.nt:]

the trucks began de iv.erinc refuse. To deter:.r.e :r. r.-mbe. of l r.'a

escap:r.g into :ne ccTpost plant as d d;:ect re'z-;t o. t;:, proved re,

the area under the cpron co.nveyo: was swept tuice da: .y; once at 7-30 a-,

before d-l'/y op-ration: began, :nd ag z.r, at c,:5 p., iT.:ed;a '/ a:-. :.

pzant closed. This was repeated for t consecutive cays during Septer oer,

1969. The larvae co elected were er.L.merated as described previous 1y.



Result and Discuss;on


Seas:onal Fluctuaticns

Tne resu'. s of a larval sample irg program to determine the species

present and seasonal fluctuations of the lacrvae escaping "nto the cc._.ost

plant are shown inr Fig. 9 and Appenrdix 2. These data show that relativ.Aly

fc-.' larvae were captured du.-ing Januar', Februar/, and March. The catch

increased :r. April wh.,e a cons ;stent h:gh number of larvae were t.-apped

frcm Junre to mid-October. Tr.e number declined thr-CghoJu November and

larvae became relatively scarce in DecemTber.

Phaen;cia cuprir.a was the predca.inant fly species collected in this

survey. Table 1 shc.is tnat greater than 97 percent. of the captured larvae

were P. cuorina. One. percent we.e M1. dc-,estica w.:.1 e the re..ainder L~.ere

cc-.pr.sed cf COchli -- ia T:c 11--ia a.or c:u.), hcr : :.llucens (Linna Ls),

cr.d S .co arm pp. T.. c c. ..a., o.- :pc c. s '.-.cs s ,.il r .-: :..cs3

report. Ly tr.2.- :.-.vcs.:;g :c... .- r cxA^ 2. -*r'" cc.,.opr.:s.d S9.'5









L
0

0

U
C
0
L.
a.
ru









4-

0-
a,


L.



L






o -
10
I--


Z4C


3 2""""t -i""I 1

M A M J J A S 0 4 D

1969 deeks


Fig. 9. Number of fly larvae
plant during 1969


caught under apron conveyor per week at Gainesville compost


(a Plant closed for repairs June 15-30.


_- less than 20 larvae


J F






19

Table 1. Percent abundance of species of fly larvae trapped under apron
conveyor during 1969.


Percent of total number of
larvae examined per week
Species Maximum Min mu.m Average

Phaenicia cuprina 100 90.5 97.2
Musca do-nestica 6.4 0 1.0
Cochlio-nyia macellaria 6.0 0 .7
Sarcophaga spp. 4.7 0 .7
Hermetia illucens 4.7 0 .6
Others <.01 0


percent of all larvae collected from residential refuse containers in

southern California (28, 18, 79). It was also the principal blow fly

found in garbage in Orlando, Florida (31). Green and Kane (23) reported

Phaenicia was the predominant genus occurring in London during the summer.

Population Factor

Table 2 gives the calculated number of larvae collected per day under

the apron conveyor and the percent trapped in the larval sampling program

for that same day. These data indicate that an average of 0.99 or approxi-

mately 1 percent of the larvae under the conveyor were caught in the trap.

The variance of 0.04 for these results indicates consistency.

Larval movement into the plant was not limited to the area under the

apron conveyor as migration from a pile of refuse could be expected to

occur randomly in all directions. Larvae migrating from the refuse in the

receiving building in an easterly direction found harborage behind a

wooden retaining wall. This was approximately 1 m from the outer wall of







Table 2. Total number of larvae collected under apron conveyor compared to number of larvae
trapped the same day.



Sweepings Sample Larvae/ No. larvae No. larvae Percent
(Kg) (Gm) sample collected trapped trapped

19.0 976 1741 34,100 487 1.41
27.0 1894 2676 38,200 452 1.17
1.8 200 1500 13,500 114 .84
18.4 642 3842 109,500 986 .89
10.7 1076 6855 67,980 297 .44
14.5 1009 4873 70,250 602 .86
9.8 673 1993 29,100 238 .82
17.4 862 1758 35,731 411 1.15
16.3 611 1796 45,851 490 1.07
22.2 885 3979 97,600 1294 1.31
Average .99







the building and extended the length of the receiving area. It was

difficult to sample this area and the larval population was an approxima-

tion based on visual observation. It was estimated that the number of

larvae escaping behind the east wall was approximately one-third of those

escaping under the apron conveyor for any given day.

The construction of the receiving area and the practice of handling

the refuse greatly reduced larval survival in other directions. Refuse

was deposited toward the east wall and as it was moved into the hopper

from east to west by the front-end loader, those larvae migrating in a

westerly direction were scraped into the receiving hopper. Northerly

migratioii resulted in little survival since the ramp and paved areas

provided no protected areas for pupation.

Coi-bi6ing the estimates that two-thirds of the larvae migrating into

the plant enter the area under the apron conveyor and 1 percent of these

are trapped results in a population factor of 133. This factor may be

multiplied by the daily larval catch to give an approximation of the

number of insects migrating from the refuse into the protected areas of

the plant. For example, Appendix 2 shows that 6116 larvae were trapped

the week of September 7, 1969. Multiplication by 133 gives an approximation

of 813,428 larvae entering the plant during that one-week period.

Effect of Clearing Receiving Buildinq Caily

Larvae collected under the apron conveyor during plant operation

were compared to collections in the same area during off hours. The results

are given in Table 3 and indicate that an average of 38.5 percent of the

larvae escaping into the compost plant migrated from piles of refuse

remaining in the receiving building after the plant was shut down for the








Total number of larvae collected per day under apron conveyor
caught in the same area during the night.


compared to the number


Sweepings Sample Larvae/ No. larvae Total daily Night catch
(Kg) (gm) sample Time collected catch Total catch

7.22 725 3400 D 36,180
2.95 351 3612 N 31,800 67,980 46.8

11.35 666 2508 D 42,700
3.18 343 2971 N 27,550 70,250 39.2

7.95 360 794 D 17,500
' ]85 313 1961 N 11,600 29,100 39.8

16.8 722 1318 D 30,700
.65 140 995 N 14,620 45,320 32.2

16.3 611 11156 D 44,400
3.35 283 2914 N 34,500 78,900 43.7

19.06 602 1992 D 63,200
2.57 282 2834 N 25,800 88,900 29.1

Average 38.5


= 7:00am 6:15pm
= 6:15pm 7:00am


Table 3.





23

day. It is obvious from these results that not storing refuse overnight

would reduce the number of larvae entering the plant by more than 35

percent and decrease the ensuing adult population.

The value of clearing the refuse from the receiving area daily was

further demonstrated by observing the large numbers of larvae along the

eastern edge of the approach ramp. When refuse remained on the approach

ramp for several days numerous larvae migrated from the refuse and fell

to the pavement below. On several occasions when this occurred fly larvae

were so numerous that the pavement along the edge of the ramp appeared

white. On one such occasion the pavement was swept clean and the larvae

collected 12 hr later. Their number was estimated to be 30,000 or 60,000

per day migrating from the ramp (Fig. 10 and 11).

Adult Development from Larvae

The majority of the larvae that migrated from the refuse were mature

and thus required only a suitable pupation site to develop into adults.

This was demonstrated by placing iO0 larvae collected under the apron

conveyor into waxed paper cups (0.946 1). Twent,-five gm of refuse debris

collected from the same area were added to one-half of the cups. The cups

were covered with cloth, secured with a rubber band, and placed under the apron

conveyor. Ten.days later the number of adult flies that had emerged were

counted. Nine replicates of each test gave an average of 65.3 percent

adult emergence from the cups to which only larvae had been added, and an

average of 88.8 percent adult emergence from the cups with debris added.

Generally there was a considerable amount of debris under the apron

conveyor and behind the east retaining wall, the main areas of larval

infestation. It was concluded that most of the escaping larvae reached































Fig. 10. Eastern edge of apporach ramp.


Fig. 11. Fly larvae along base of eastern wall of approach ramp.









adequate pupation sites and close to 88.8 percent adult emergence wlas

expected. Extending the previous example given for the week of

September 7, 1969, an approximation of 733,313 adult flies could be

expected to emerge within 10 days as a result of larval migration fr-om

the refuse.

Survival of Larvae Through Grinding Mills

Approximately 10,000 mature house fly'larvae were passed through

the secondary grinder in May, 1969. The primary grinder was not in

operation at that time because of equipment failure. Nine live larvae

were recovered in the discharged refuse. In July, 1969, 10,000 mature

house fly larvae were passed through the recently installed primary

grinder. No surviving larvae were found in the discharged refuse.














SECTION II


CONTROL OF BLO. FLIES



Studies were initiated in June, 1969, to evaluate several procedures

such as mechanical control and insecticide baits, fogs, and residues for

the control of blao- flies emerging from the incoming refuse. The

effectiveness of a control measure was determined by the reduction of

flies caught in two baited traps located behind the receiving building.

These investigations were terminated in October with the advent of

cooler weather.



Blao Fly Traps


A suitable method to estimate changes in the number of flies was

needed to evaluate the various control procedures. Sticky tapes were

ineffective because the large amount of dust created in the receiving

area rapidly coated the adhesive material. Grill counting was ineffective

because the counts varied with hourly density fluctuations and positive

species identification was nearly impossible (42, 45).

Norris (45) reported that bait trapping was the only generally

useful method available to study blow fly populations and that the bait

employed was the most important variable. He reported that animal tissue

was the best for blow flies, being more reliable than some of the more





27

recently developed synthetic attractants (14, 45). Ho:-.cver carrion is

not a uniformT bait. Its attractiveness varies with zae, moisture, and

deco:r.iposition (42). Ka.a: and Suenaga (S3) fund that fish 1-da'y-old

vwas tne most attractive to b,1 .-. .'ies.

The traPs se;'ctecd o." L e :: t. cc.pos .b r.. C' e '.o C .< 3 o .\

54 cm :n'.erted cone traps. The- were :ated 'i.1 :-d-y'-olo fish .e Ds

acquired Ioca l'ly. "ns asa of each trap .as encloscc by C.5 c:. sce..-.

wire to prever.t s.:all ar.;rals from sea .g :.'-. b.-: Tncse traps ..

sho.-in in F ; 12.

The tr.ps w'.:ere pieced on the pa'.zr.an: behind the receiving area,

see Figs.l and 15. The flies .were collected frcm the traps daily by

plac .-. the trap and '1 mi of eth',l acetate into a plastic bag. After

the flies %-.cre anesthetized, they were removed and placed in:o a small

plastic bag. T..e catches were then transported to tne laboratory for

coLr.cing ar.d identification.

Tab e 4 gives the ioenrtfication of flies caught in 15 different

daily catches. Tnis shows that 89 percent of the fiies trapped were

Pr.Lcr, icia spp., 6.8 percent were iiusca dciiestica, 3.7 percer.t were

Cochlic.n'-ij miacellar a, an.d 0.5 percent arcoohaqa spp. These figures

are close to those percanzag.s recorded in Table I which gives the

relative abundance of the various species of !arvae entering the plant

frc- the refuse. The differences that occur may be the result of the

trapping method e-.ployed, different survival rates of the species

involved, or ir-migration of adults from surrounding areas.































Fig. 12. Cone trap baited with I-day.old fish heads to sample fly
populations at compost plant.


Fig. 13. Rear view of receiving building showing receiving
hopper and pavement behind building.









Table 4. Sex, species, cr.d abur.nd nc- (;.,, c.f fli is c-ught in con.e tr.a.Ms
baized w\. chr 1-day o'd .:sh -.earls at Ceinesvillie coposci plar:.



erc r.._ C: Co ..
Spez ies .. .. .c.-J_ ,, L.-a *.. .'-, .m-- c

P c-.- r.-c a spp. C3.0 10.4 c' ."
;.LSC ac.-Costica 6. c 1.7 5 .c
Co:hi ia-.'i- -n-cel la.-' a ;.7 55. 2 ,*.:
rco haqa spp. .5 .t'3 iCL..j


atiean of 1- day catches zaken a- random.




F Ild Tests


Petr.ocs

Several adL't fyi cont.-oi procedures v. er evaluated to ceterm i;ne

their effectiveness and cost of app! cation dur r.g the summer of 1909.

The effaecr eness of th- ccnc.ro proc-cures w-.as determined by c cn-parirg

the number of flies caught per day in baited trap- during the treatment

period to t.ie nur.ber of f' "es ca9ugt dLur-r a prior period of no crea=-

mer.t. T..e duration of pre-treatT.a-.n ccntrcl spimpling wjas 7 days and

subsequent cc.,troi per ocs were 3 days. ,.reatmenc and control periods

were alterr.naed and fo;laJ ed c;h.c.-.olgc.ca'!ly :.i ;he order presented in

Taole 5, beginning July 14,, 1". fcjr :n 5 c'y/: elapsed between a

treatment and the c.auoing control .:r;oc.

The control procedures are descr bed as follao-s:

Sutr bi -- KcK:Ilr ~: al. (1) :n stud~, s L; durops fojr.d ':.i. t

trich.orfon b .:s g ve 'jc o.-.roi cf blo. f'". Sai;,'l c: a ()

re-o.:c.. t-,t di:t.. rvc: ..-. -..: so Ijcr a i:s cc;trollcd ho-se fl :e .






Table 5. Number of flies caught per day in cone traps baited with fish heads as a monitor of
procedures to control adult flies at the Gainesville conpost plant.


No. of flies caught No. of flies caught
per day % per day %
Day Control Sugar bait Control Day Control Sweepingc Control

1 2343 15-18 -
2 2796 19 1197
3 2268 20 2316
4 979 21 1954
5 1050 22 X = 1822 856 53.2
6 3456 23 1055 41.9
7 824 24 908 50.2
8 X = 1959 1178 40.4 25 667 63.4
9 875 55.4 26 353 81.6
10 285 85.5 27 1061 41.6
11 596 69.7 28 1775 3.6
12 1041 47.1 29 1493 18.0
13 490 75.0 30 1437 21.1
14 107 95.5 31 1315 25.8
x = 653 66.7 32 988 46.4
x = 1083 4.6


aNumber of flies caught per day when no control procedures were used.
b400 gm of 0.5% dichlorvos in sugar mixture applied daily as a bait.

CArea under apron conveyor swept daily.

Mean values represent the mean number of flies caught per day for that given procedure (column).







TI11 c $ (CoGt n1u1. I)


INo. of f 1 i s cai.l l;ht
_ _p.er dy
Colitl olflt ait


1 711
1397
1965
X> 1 6., 3


360
511
641
1 21i5
14167
597
1017
> = 831


I,:,. f fl i c, :u L l t


Control


Pay


78.8
69J. u
62.3
26. 7
13.8
6'. 9
510. 1
$1..


____pr 'd .'
Control


1 96/
191:





60 7
1 9i :







1601
18 1.


561
6":
r,61
V 5, '


Cont rol






7 7
65.5
70.7

67.3
1 0

5.2


12uC ml o' 1 .0": Cicil orlvc in 5r, rntil t olutioii, ap lied diil 1 a. ca L.i t.

I of 5.0/ feCnthio n in (Jo. 2 fuel oil appr l licJ ith a l ,c-. c : li0o;--aii- s :iI r. iJjer L.I dacl 53,
5'., aJ 55.


33-3(.
31
3 8
33J
*:
I ,



' 5
/, ',


47-5






Table 5 (Continucd)


No. of flies caught No. of flies caught
per day % per day %
Day Control Dimcthoatce Control Day Control Gardonai Control


28
"13
37
18
64
49
112
287
170
393
811
1256


76-80
81 1677
82 1170
98.5 83 1410
99.3 84 = 14]9
97.9 85
99.0 86
96.5 87
97.3 88
93.3 89
84.9 90
90.6
78.3
55.0
30.1


1056
653
1251
734
949
781
1090


25.6
54.1
12.0
48.4
34.4
45.0
23.3


g10% dimethoate solution applied at a rate of 2 gm (AI)/m2 to grassy areas adjacent to receiving
Building, one application on day 63.

h0% Gardona solution applied on day 83 at a rate of 2 gm(Al)/m2


1437
1719
2241+
x = 1799


--






33

Fly Bait, a 0.5 percent dichlorvos sugar bait obtained commercially from

the Fasco Chemical Co., was used prior to this investigation to control

the flies at the compost plant. This bait was evaluated when applied

at a rate of 400 gm per day. The bait was distributed along the conveyor

belt system for a 7-day period beginning on day 8 of Table 5.

Sweeping to remove larvae. -- The area under the apron conveyor has

previously been shaon to contain the majority of the larvae migrating

into the compost plant. To determine the effect of collecting and

removing these larvae on the total number of adult flies, this area

was swept daily for 15 days.

Malt bait. -- Malathion, diazinon, chlorthion, and dichlorvos in

malt or molasses were reported to be highly effective liquid baits for

blow fly control around dumps (76, 31, 34). A dichlorvos and malt

solution was used to determine the value of liquid baits for the control

of flies at the compost plant. Blue Ribbon malt was diluted with

distilled water to form a 25 percent malt solution. Technical grade

dichlorvos was added to produce a 1 percent dichlorvos solution which

was stored at 4 C until used. Fifty ml of this solution were applied

daily to each of 4 locations along the conveyor belt system for a 7-day

period beginning on day 40.

Foqqinq. -- Fogging is not a highly recommended procedure for

effective control of flies since fogging leaves no residue and a high

concentration is necessary to kill flies. However, the effectiveness of

fogging was evaluated since it was used to control flies at the Tennessee

Valley Authority com-post plant in Johnson City, Tennessee (61).

It was observed that the adult blow fl ies, predominantly Phaenicia

(Table 6), left the building at dusk and roosted in the grass irr.mediately











Tab!e Sex, -pcc es, and U.i.-C, ncc ('I' r f. 'c Cc .'lt by L. : t1
ir. Lrass -c cc ." LO rce.: r..] c-r. C Inesv.l il e CG...,c..
plant.



Prar.n of -
Spac es flie- c- : .' ,.'...
SI ICcC..S .f II e L L

3. Caught dur:r.g day
Phcanica sp?. 95.2 .3.1 56.
ML sca do esT ica -. 32.3

b. CucLgt a: r.igh-
en c:a .. S .? -.3.7 5 .
"usc, cc- s: '.c .3 S3.7 ..


a
I;.er. of ten s p.-.ples taken by fi.ve sweeps of net.



surroJndi.-.g :ha plant. Thesa areas were fcged az 9:0O pm or. day 53,

54, and 55 (Tabse 5) e icn a 3 percent fenathion :n \o. 2 fuel o;. sciutior.

d;stricjtt d by a portab:. ht-ci-r suing .ogger. This insectic:d, a-s

selected because o.- avii.biiiy and LaczJse a 5 percent fenzhion soition

k;ll>d 97 perc.-i: of t:-. caged :-.c-se flies 50 m froir a moving foggLr (4).

Resl -al srrais. -- Cc.tact a.id residual sprays are the most oftter.

recorm.ended methods of cc.ntroll ir.; flies. These sprays are r..cst cfrect ve

.whn applied to fading a ras and night-t ire rcting places such cs

shrubs and plant, in th- _irro.dir.ng area (34, 76).

SD;mt.-,o~te gave nme best control of hose fl es in Florida dair', barns

when applied a: a rate of 2 gm (Al)/.,- (5, 9, 10). A 10 percent dimuthoete

'.r. .w :, so.Iu.c i -p. iLc c..cc c.'. dy 3 -y a 2-g: al n F(.57 1) C.r.-

preosed-c Tr r.,. . -.',' c. .-* u ". 2 .,.. i..-../ tne grassy areas

surr c. .- .ac t.'- ., r...






Gardona, (2-chloro-1-2[2,4,5-trichlorophenyl] vinyl dimethyl

phosphate), a house fly larvicide, was provided by Dr. G. C. LaBrecque,

USDA Gainesville laboratory. A 10 percent Gardona in water solution

was applied on day 83 in the same manner as described for dimethoate.

Results

The results of the field tests are presented in Table 5.

Sugar bait. -- Daily application of a 0.5 percent dichlorvos sugar

bait reduced the number of flies trapped by an average of 66.7 percent

when compared to a previous 7-day period of no treatment. This control

procedure cost about $3.00 plus 0.5 man-hr per 6-day work week.

Sweeping to rer.ove larvae. -- The area under the apron conveyor

was swept daily to remove the larvae before they developed into adults.

An average of 40.6 percent reduction in the number of flies was noted

when compared to a previous 3-day control period. This reduction is

considered to be a minimal value. It ..as significantly lower than

expected since previous estimates indicated that 67 percent of the

larvae that migrated into the plant escaped under the apron conveyor.

The difference between the observed and predicted reduction may have been

influenced by the short test period. Since the larvae entering the plant

required 8-10 days to become adults the 15-day study period may not have

been long enough to ascertain the true results of cleaning the area.

Regular cleaning over a longer period should reduce the adult flies by a

factor approaching the percentage of larvae escaping into the area.

A second factor influencing these results was the operation of the

plant during the test period. Mechanical problems prevented regular

operation of the plant and refuse remained in the receiving area for








several days. This resulted in larval migration patterns differing

from those encountered under normal conditions.

Since the larvae entering the plant required 8-10 days to become

adults it is reasonable to assume that cleaning the area once a week

would produce the same results as daily cleaning at a reduced cost. The

effects of cleaning over a long period were not investigated.

The area under the apron conveyor could be cleaned once a week at

a cost of about 4 man-hr.

Malt bait. -- A 51.2 percent reduction in the number of flies was

observed over a 7-day period with the application of a dichlorvos malt

solution. This bait was found to have several disadvantages; (I) it is

not available commr.ercially, (2) it must be stored under refrigeration,

(3) it costs more and was less effective than dry sugar bait, and

(4) its syrupy consistency made it inconvenient to use.

Foqqing. -- The grassy areas of the compost were fogged for 3

consecutive nights producing an average reduction of 68.9 percent of

the number of flies trapped on the folla-ing 3 days. The effects of

fogging were minimal after 1 day as shawn by the post treatment counts

in Table 5. Thus, an effective control program would include a minimum

of 3 foggings per week. This would cost $15.00 plus 3 man-hr per week.

To determine if this fogging procedure was effective on P. cuprina,

100 adults were caught at night by a sweep net at the compost plant and

placed in a gauze cage. The cage was placed in the center of the grass

hill during the fogging operation. After the area was treated the flies

were transferred to a clean cage provided with fly food and water and

held for 24 hr. A control cage was set up and the fly mortal ity obse.-ved






-7

in each. r. is roc .ure' as cd p. 'd .:or c :h treatT.er-. An cVerace

of 97.2 percent of the tre::-d fl ies w- ere dad crter 24 hr whilee 6.1

percent mortal i:y was o'sas.r.'cd in the con;.ol cages.

Pesidual s rav, s. -- A ...C e ., o. ic:tio of dir, thoate gave better

than 95 perccnit cc-.tr3. _.- :.e : ies fc.- c te:e cid re,.-a rned e-,:.: .ve

for 10 days as shoin ii Tab'e : The cost cf cne apl ication vas

approx:.-ateiy $7.00 plus 0.5 m.,n-hr.

Gardcna '..as ir.nefi:ct ive as a r; 'dual spray for the control of

blo.- f i;es as sho.-in in Table 5.

Larvicides. -- Green (22) demonstrated that 59.1 percent orf -,ne

larvae escaping from s, ending refLuse :-a'ns could be controil1c b' dustirng

the area twice wee.
ur.der tne apron ccnv ',,or to control b"..k fl ics iwas rot atte7m.pted because

c: the large amount of debris fall :.-g daily i-to this area. The effects

of the lar.:cide woj.c be short-l: ,ed since incom-ing larvae probably would

not be exposed after 24 hr.



P.rari -c 61 Flies


e-'.thoas

To screen :n3ect cides ir. the Iaboratory fo,- their effectiver,ess

against P. cupr rna : w firs c r..cesscry to "ind a suitable reari..g

r.edoum so i;rge r.Lr.mors would be a'.vilabl . P. cuori..3 are easily reared

.i t'ie la borator..,' on a c.:t of Lecaying meat bt this medium is odoriferous

and also expor.siv/ .hu .rn l:r : r r._.nbc-rs of fl 's are rc-jired.

lga .'t n P.s s ': b.t a,~. l.T c. r,.. c .. _,r ,;oo.. .. n m Xi. cst i-

gaticr. was sta.r a to c-te.'r .r.. "- ... c.- *-c: .:.her :.._ ria. ,rricht b;






38

substituted for meat. Two series of tests were carried out which varied

the amount and kinds of test media used. In the first series the test

medium was placed in waxed paper cups (88.8 ml) with 200 P. cuprina eggs

collected from wild flies captured at the Gainesville landfill. Each

cup was then placed in a waxed paper cup (0.946 1) containing approximately

20 gm of dry builders sand. The larger cup was then covered with a

black cloth and secured with rubber bands. Eight days later the mature

larvae had pupated in the sand and the pupae were removed from the

medium by sifting the sand through an 18-mesh sieve. The pupae were

counted and the number recorded. One hundred of these pupae were randomly

selected, washed, dried on paper tacels, and weighed on a laboratory balance

(Mettler, Evanston, Illinois) to determine differences in the size of the

pupae reared on the various test media. Six replicates were prepared

for each medium.

The media tested included the following: lean ground beef; Alpo,

an all meat dog food; Chunx, a dry dog food; Strongheart, a canned grain

base dog food; and Chemical Specialist Manufactures Association house

fly rearing medium (CSMA). Various amounts and combinations of these

media were used as sha-vn in Table 7. Meat was added to several test

media because P. serricata was reared on CSMA fly rearing medium when

provided with sufficient meat for the larvae to develop to second

instars (35).

In the second series of tests 1 ml or approximately 6,500 P. cuprina

eggs collected from wild fl ies were placed with the test medium into

4 x 15 x 30 cm enamel trays. Each tray was placed on approximately 5 1

of dry builders sand in a 40 x 55 x 25 cm plastic tub. A piece of one-fourth





Table 7. Analysis of several rearing media to determine the most suitable method of rearing
Phacnicia cuprina.


Pupca developed Mean weight
Test medium % No. 100 pupae (gm)

a. 200 P. cuprina eggs + test medium placed in 88.8 ml paper cup
10 gm lean ground beef 81.55 163.1 1.513
25 gm lean ground beef 83.05 166.1 2.154
25 gm Alpo 82.4 164.8 2.067
15 gm Chunx + 15 ml water + I gm Alpo 80.1 160.2 1.501
15 gm Chunx + 15 ml water + 1 gm beef 86.4 172.8 1.514
10 gm CSIrA + 20 gm water + I gin beef 73.5 147.0 1.217
15 gm Chunx + 15 ml water 63.05 126.1 1.311
10 gm CSMA + 20 ml water 0 0 --
5 gm CSIIA + 7.5 gm CHunx + 17.5 ml water
+ I gm beef 80.4 160.8 1.533
Stronghcart 59.8 119.6 1.201
b. I ml (c.a. 6500) P. cuprina eggs + test medium placed in 19x30 cm
enamel trays
250 gm lean ground beef 26.5 1723 2.308
454 gm Alpo 34.8 2266 2.226
100 gm Chunx + 400 ml water + 50 gm Alpo 48.6 3160 1.689
400 gm Chunx + 400 ml water + 50 gm beef 62.1 4040 1.719
250 gm CSMA + 500 ml water + 50 gm beef 47.6 3092 1.078
100 gm Chunx + 400 ml water 17.0 1108 1.787
200 gm Chunx + 125 gm CSIMA + 450 ml water
+ 50 gm beef 52.1 3391 1.416






40

inch plywood with a 25 cm diameter circle cut in the center and covered

with muslin cloth for ventilation was placed over the tub and secured

by 4 bricks. Eight days after egging the medium the pupae were removed

by sifting them from the sand and the total number recorded. One hundred

pupae were then randomnly selected, washed, dried, and weighed. Six

replicates were prepared for each test medium.

The test media included lean ground beef, Alpo, Chunx plus Alpo,

Chunx plus ground beef, CSMA plus ground beef, Chunx, and Chunx plus

CSMA and ground beef.

Rearing tests were conducted on the screened porch of University of

Florida building number 618 which is located northwest of the medical

entomology laboratory. The porch was screened on 3 sides and covered

with a roof with 1 m eaves. Light, temperature, and humidity were

ambient. These tests were conducted during May and June of 1970.

Results

The results of the rearing tests are presented in Table 7. These

data show that i-mmature P. cuprina reared on a diet consisting only of

meat were larger than those reared on the other diets. When large

numbers of larvae were reared, as in the second test series, 4 of the

diets produced more flies than did the all meat diets.

The diet of the dry dog food, Chunx, plus water and 50 gm of ground

beef was cnosen to rear the flies used in the laboratory chemical

screening tests. This diet was superior to all other diets tested in

the nimnbers of pupae produced and cost less than the all meat diets

without producing offensive odors. Although the pupae were not as large

as those reared entirely on meat, these size differences were not








con.sid,.rcd ;reat encugh to ad-ersei' a-fect the teits or offset the

advanzSges of the ccg fco dI-.

Adult bl cow vlis usC in :~ chC-:cal scrcer.ing tests 'were rearec

rC .."i ,>, i co c :c a . ... .: : -

f' s -.ere re.-c to i-. .-. -er. r.---z: .0 c. . -... ... e: cc,'.ii -.:.- c.,

4CU 9gn CV..r.x, -.CO .ml tap .'a er, and S 1, !e .r, gro-nd beef ;.- r:-.-.r..-

described above for the second. :s: ser-e:. Aul: fi ies wr--re h!d .-

15 x 24 x 50 cm- gaSzc.--overed ca, es arc prov ded w ith fras zl: -:zr r.d

fly food daily. The fly food consise. of ,arrs 9ranulaLte sugar,

6 pa-ts nor .-fe d.y i/ i .<, n.d pa.-t c'ied ec-g olk. T'e cages --.ere

:-. d .r. the Un.ivers ity c/ Fl orida :.-aoicl n:C.o g'.. la, o rzz :y

er.,.iro, .ent-- con :tr cha.mn er .' h hr of artificial oa l ight

provide y Ir.ca.,descent lights. Temperature and hu.. idi;/ were ma;r.-

ta:ned a 2 at 2 nd 70 percent -..



Labcratorv Screenina of Insecticides for
Co.nrol of 2. cp. ina



Met hods

Five-day-old fe -aie P. cuor'na adults '..ere exposed to space sprays

cf 12 ccc.mr.erciall 1 av.ailabIe inscct;cides in the wind tur.nel described

by Dav;s sand Gzhan (15). Tne insecticide solutions were prepared oy

disso!vin each chem.- al in acetonc to attain the desired cor.centrations

(w/v). Thc original range of co.;centr options for eazn chemical was based

on the LC, values obtained fo: .r. insectC:cde SLsceoibl e stri:n of

.-cuse fil:s at -.; LC:.. La.-cra:.-y, C&:2.--lv>;'e.







42

The tests follaoed the procedures outlined by Bailey et al. (7, 8).

Twenty adult females were confined in test cages made of metal sleeves

closed with screen -';ire at each end. These cages were placed in tne wind

tunnel. One-fourth nil of the insecticide solution was atomrized at 1 psi

into the mouth of the machine, and drawn through the cages by a 4 mph

air current. Duplicate cages of flies were treated with each concentration.

mrrnediately after treatment the flies were transferred to clean holding

cages and a cotton pad saturated with a 10 percent sugar water solution

was placed on top of each cage as a source of food and water. The

treated flies were held under constant light at 250C and at 70 percent

RH for 24 hr when mortality was recorded. If the concentrations of the

chemical tested produced greater than 90 or less than 10 percent mortality

these data were discarded and other concentrations selected until a

minimum of 4 concentrations were used that produced mortalities within

the acceptable range. These data were used to calculate LC50's by the

probit analysis technique described by Finney (19).

Twelve compounds were evaluated in 13 tests, each of which included

from 4-7 insecticides, acetone, a dimethoate standard, and an untreated

check. The chemicals tested were as follows: dimethoate, parathion,

naled, diazinon, fenthion, ronnel, propoxur, carbaryl, malathion, Dursban

[0,0-diethyl 0-(3,5,6-trichloro-2-pryidyl) phosphorothioate], Gardona

[2-chloro-1-(2,4,5-trichlorophenyl) vinyl dimethyl phosphate], and Bayer

41831 [Sumithion] [0,0-dimethyl 0-(4-nitro-m-tolyl) phosphorothioate].

Results

The insecticides tested as space sprays are listed in Table 8 in

ascending order of the LC50 values obtained by probit analysis. The

fiducial limits (P-0.05) are also listed. Dimethoate was the most effective









Table 8. LC50 of 5-day old Phaenicia cuprina females to insecticides
in a wind tunnel.


LC Fiducidal limits LC susceptible
Insecticide (%i P=0.05 hose fly (%)a

dimethoate 0.0259 + 0.0064 0.04
parathion .0532 .0068 .05
Dursban .0567 .0063 .74
naled .0648 .0065 .018
diazinon .0857 .0063 .062
Gardona .126 .0063 .06
fenthion .133 .0065 .15
Sumithion .183 .063 .074
ronnel .246 .065 .13
propoxur .264 .092 .95
carbaryl 8.42 .67 >2.5
malthion >50. .81


aData obtained fror, the U.S.D.A. Gainesville laboratory.





chemical tested and along with parathion, Dursban, naled, and diazinon

demonstrated potential for use as a chemical control of P. cuprina.

Gardona, fenthion, Sumithion, ronnel, and propoxur were less effective.

Carbaryl and malathion were ineffective with 50 percent malathion failing

to kill 87 percent of the exposed flies. Appendix 3 shows the concen-

trations and percent mortalities used in the probit analysis to calculate

the LCc 's. The Chi square tests for chance variation of a homogeneous

population were acceptable at the 5 percent confidence level for all

tests and are listed in Appendix 3.









The CC0 a!ues obt.:rt; by tr.. U JS CIinc.i..i Lascrato.y .;
10
th Orlan.do SLusc-.t-t .r-in cf h, se- f: les .'or tie in-u, ct ici' s

te -eCd are I isted in Tab> : T.hee '. .. c.h.; c jT.-xc ed tc zi '.- 's

obtained it.-. :: c i . lc.] : c .: -, : '.:. a r;zasc:-. :, ccrr la: a :. eo'en

of :. e chc..:2:s -:C .c J c. -.-. s :.-S a v . s fcr .-c.-c .

bl .ow lies w.thir a factor of 2. The tolerance o. .;. cu L ir to t.ln s,

insecticides zppea.-ed to b. abcL tr sZ. .5 ; as '",0:O cf the u-scC t.,:

house fly s:rair. colc.r i-ze. c.c.- ; '/e,- a.o. Tr.,s is L.-.c~tstLcr,"' .e

s nce the bl a- f;y ..as r.ct been cer.cra.ly expO d ,t3 : o iisect;icidal p-ressuLres

over a -.id spread are3 n the Un:-:d Sta:je.

,.ie Ir.f.fe t e v ensess s f r.. ::.-ic. t to kil C. cuorir.a *..s u.nec oectec

as m.:cr.n;cn res :duz sp-ac's hva -.en re:cG=e..-.d-c to control bic.- fl ies

.t Florida ari'ps (34, 79). Th:s becomes less startling, ho.:.ever, -:hen

one c:nsicers that T..a:tni on. cid not cPr.:.-o1 CL'pr na on shucp in

Australia k57) and znaz r .:cr, has ir.ducea a very specific resistanrce

in the hcuse fly, in CJle: :a-s-: is C q. aid in the blo.- fly, Cr.r'scTivia

outoria Wiea. (1). .n the case of tr. blao fly, cariplate resistance

was induced within 6 months.

P. cusrine are controlle J n. Australia ar.d widespread dieldrin

resistance has bcen reported. 'wild f lics .cre i;c t imes more resistant

to dicldr.n th-n a susceptible strain and resistance, was also obscrvd

to aldrin, endri., isodrin, cr.:crdC..c,, other :yclodicncs, ar.d B..C (32,

67, 6d). Since th, general us- of chlor;nated hydrocarbons is i'iegal

in Florida these chenmca's were not tcstLJ in 2, stjd.,

A shi-t in ;h. cot.-.r.C of b:., .: L. to c.-z- ic p;.osphLas ra made

in Austrc: iO ..-. :.-.: ,a e ;S 's. i&zia ;cn ..~t :t ?rims ry insecticide


-.-'-I





45

used and according to Shanahan (70, 71, 72, 73) no resistance was found

after 6-8 years of use. He terms a 3-5-fold increase in the LD50 values

of wild fl ies as tolerance. Schuntner and Roulston (65) found resistance

to diazinon in blci flies and identified it as the breakdown of the

in vivo pool of free diaoxon. A perusal of the literature revealed that

resistance to any insecticide by P. cuorina has not been reported in

the United States.















SECTION III


DENSITY AND SEASONAL FLUCTUATIONS OF
HOUSE FLIES AT THE COMPOST PLANT



Observations conducted during 1968 revealed that bla, flies and

house flies were present in large numbers in the receiving area and

around the sorting platform, while house flies predominated in the

digester building. These flies annoyed the workers and posed a possible

public nuisance if the plant proved to be a source of flies to the

surrounding community.

A house fly sampling program was begun in January, 1969, to determine

the density and seasonal fluctuations of the house fly population at the

compost plant. The purpose of this survey was to determine the magnitude

of the house fly population, the necessity of a fly control program, and

seasonal changes that may affect such a program.



Rearing House Flies


All stages of house flies used in this and the following section were

obtained froa the insecticide susceptible or Orlando strain maintained by

the USDA Gainesville Laboratory. These flies were reared in a 10 1 plastic

tub in a mixture of 1 part CSMA fly rearing medium and 2 parts water. A

6.5 x 6.5 x 10 cm sponge saturated with water was placed in the bottom of








the tub to maintain proper moisture. The tub was covered with a black

cloth secured with rubber bands. Pupae were collected 7 days after

egging the medium and placed in 15 x 24 x 50 cm gauze cages. The adults

were provided with fresh water and fly food which consisted of 6 parts

granulated sugar, 6 parts non-fat dry milk, and 1 part dried egg yolk.

The flies were reared at the USDA laboratory in rooms with 16 hr of

artificial light provided by fluorescent lamps. Temperature and humidity

were maintained at approximately 26 C and 70 percent RH.



Seasonal Fluctuations of House Flies


Trapping

The digesters were selected as the primary sampling area for adult

house flies at the compost plant for 2 reasons: (1) initial observations

showed that adult house flies were usually more abundant near the

digesters, and (2) equipment operation in the receiving and sorting

areas made sampling procedures difficult.

The grill method of sampling house flies, developed by Scudder (66),

was initially selected for use in the seasonal fluctuation study. This

sampling procedure results in an index of the population and not an

actual measure of population density (43). The reliability of grill

sampling is debatable. Murvosh and Thaggard (43) reported a high correla-

tion between grill counts and the total number of house flies in kitchens

on the Island of Mayaguana, while Schoof (62) found that grill counts did

not increase linearly with the population sampled. Welch and Schoof (81)

reported chat grill counting was subject to individual error and was no

more accurate than visual estimates.






S40S

Crill counting rq .na effectt ve at the compost plant because of tne

large .evolu'e of attractive mate .-ials present.

One-foot- square (32.4 cm ) masonite boar'.'- ccvercd Ly a th n la'.er

of Stickem (.ictal e1 nd Pelton Co., Emryv.;le, Califorria) .-iLr w;v-l-:cd

for tracp.ing fl -s i tr.o digc stcr. T .se o rJs '.:ei-e ctt-chcd tc stn.es

I m in I r.g:s .'-.ich v\wru then C:.'v,. :r.to :h- ccO-..ost n .h.. di. c t. -s5.

This procedure \v-.s d .scardc: because scL !arg, r.ur.bers of fl i; vw .-e

trapped that -..- beards becs:.- : .r.crfTct.vat v 2' 'O,- 2 ,- hr a h passed. M.SC,

m.or. than 1000 fla:-s per Zoard wIre trapped and a population recuiction

:his gre t n-ay hove significc-'.t1 y r:uced ch. :ctc: pouLlat'.c,.

F ., st icky tap..:s (Ac-c--.o. ?:.duc.. .... .c.. fo. N.'. ) "ras.rir.g :

o: c. '.:.'re .-t. arr cr :ha s c.y U; C %.:C r shc..n .c be ,s .

TO" trapping :,.e f i e .ayo J d (.5-, S, E) resor-2: --at s:.c',' zta.es

were -,or.e acczur- c t.ha, 11 ccu r.:.c ir. ..:. L ..-. .ouse f 'l poj -D.d.

in Africa because they wrc:-e ass depcndn t on hj.-.on 'udc,-ert, took into

acccnrt temporary :l jctu: o;.-,s in oer.slties, an.d allo.-ed for the de: nti-

fication, cf the fl ies. Sticky tapes nave also been sho.in to be More

accura-e than vaacu.um collect ions .nd visJul co-nts at poultry farms (2;,

.nd baits at dairy bar-s (51). T.sts c.ring Decreber, 1963, revealed that

stzcky ta.cps were accc-: p al for tr-pping ..ouse f, s at tne con..post plant.

ric.sc f lis were sc-.ipled in th-. digesters from January, 12 to

DecezT.mcr 31, 19'9, using st ;cky ;apes sLspn.-.ed from 1.2 rr. .ooden StaKus

driven in-o tne cc-' o... Five stakc, were ,Tp' oy.ed d-ily '.d each s :ke

w.;as placed in a diffcr;r.: 3ag of conpcot va.ry.-.j fro-m l- days of CgJ.

. .k;" : .. .. .* r..-::. ca .y cC i. L.,- r.. .-C, c r.cuse :..s CuL .-.: 01

rc acr. ... e o: t'. ca .os :.. .a. t .per.dcZ r.*c

r uc or: c:.






-9

The mear. numoer o. fl 'e ca.-.t- per sticky tape per ue&k .a cacu-

Sated by 'di.'iT r.; t-e r.j.-b~ C f ;.s ,c ugr.t per w.e
st cky rapes. 7rese ca aa e sn,:.-n i. Fig. 14.

Effects of Te-: .-atre

The' m xrr.'-, au-;; c. ..'- .. l u., .T-:' .': .- re rs '.. cr roGce .. Z 1

3 5e sz..-,ace treat e.n racil t,, .ic.I -s c Ioc'n i me "y ce.".

:o the compost plant. T.i es c-ta .- -a m:Zace av.aiab.e :hro t.-.e

c t-rzesy of Mr. C. '.. Lenrat, n najer of t:e treat..er.:t fa :'/. ri.c

.aeekl', .means of the imzic.ar da1 y s.:- Tpera.ures w.ere calculated ar.d

are sh: .-.o n i n -. . .

A co,.par sot, c. tre rca-. : .e.' c:tch of f. s r. .:-. -- :-rs

th.e rme.,n vjc m:.x mu.. a: r :.-:er :Lrcs sr .... an a:pare-nt corre.a: Cr.

betw.'een- these data fro,. J',uary/ tc J-r.e. T.c cc-r.posc plant was closed

to replace the prTimary grinc :rg mill on June 15, 1959. L'her. ope-ations

resumed c.- Jj1 6, a c ':.'ize c.-op .r' r.u:be,-s of trappea flies v.wa

observed. A. check w.':n tne plant foriT-n -rv ,ealed thsa: he operating

procedures were the same as tr.ose before .he plcr.: closed for repairs.

The oly sserv.aole difference was ch.a the ;e:L.se d:sc:a-rged into Lhe

d;gesters was sl ightly snmal ler in size. There was no reason to bel ieve

thaz this would greatly affc: ,zne nu, e. of :l ies in th. area.

1: wa-s ooserv.ed nmat ter..cerZtures in the digester builainS w.,-re

higher than the -..iblent air :e.T.pcra-:Cu.'eLsbecause o.: the heat generated in

the co.T.pozting p-ocec-a and the cons:.'uction of the il-Il digesting

build ing. A .yc ro t-.rcorcaph was p accd on a platforrmI 15 cm abo;e rne

c -.c :he ; r :c : s .er L:e- w.r, .- .cord d for se ,vera

t-. '0 k r.-: '.".. :.- ..:, :ve.-. :.. 7 :. ,-,.C t t tz-.e eajr daily























06 0


I.


-v
L.

Q..






Ic
U









u
a,
a)
4-


(U
-o








IP -


60.
.0 9


0
* go **


23 9 23 6 20 4 18 1


15 13


27 10 24 7 21 5


19 2 16 30 14 28


J F M A M J J A S 0 N

1969 Weeks


Fig. 14. Mean number of adult flies captured per sticky tape
digesters at Gainesville compost plant.


per week during 1969, in


(a Plant closed for repairs June 15-30.


12 26 9


080


foj
35 n-

-o 3
on,
30 1

CO 0

25 3
n X
3
20 c
0-

15 -
-






Table 9. Air temperatures recordeda 15 cm above conpost in digesters at Gainesville c-npost plant.


Mean daily
high


1969 Wcelk of


41.6

37.5

37.3

33.7

33.3


Mean daily
16:1l


34. 1

32.4

31.6

24.2

20. 1


Mean hourly
temperature


37. 1

311.9

34.5

28.5

24.0


Na f ics caught
per sticky tape


9.0

9.9

13.0

77.3

51. 2


Aug. 17

Sept. 21

Oct. 19

Nov. 16

Dec. 21


Degrees Farenhcit recorded on a hydrothermograph converted to degrees Centigrade.

See Fig. 14.









|m.,x:mnum ir temperatu.:c in the dlcj.ster Lu:lding cculc b- expected cc

exceed 37 C during :he SL--.rT r r.on ns. Appcrently/ hthse tg.-ceuraturei

discourageJ the flics frc.m entering the building resulzir.g in a laer

number of flies trapr-d c,.- the cricky,' t p es.

Tna nur.-,br of f; :e tr:,cc :ncre:-c_ n a.l OcLar .wh.

decrease .-- obsc.',v d .n ne c.-ricr.. -. r .T.p:r.._r- cr.d t:- ,.-.7 .ra. r.

in the b ild:r.:. Tn.;Lu bs 'rv/r.::.". c-..d c.r d-r.c. :a :h.e c-: .'.r :.

the fl ies w.:re re l: i bc.aus c, t.-.e h.gra.- :-T J.- Lr .

r, c c.-C ease -. t:-.e r....nber of f ies ard .-na Zi.b:ir.t ai.- tCeT.,m ratu-c

w s o0asuved in Dec-mber.

Th :s invcs :.; ric.-. V s o.-:c!r.a.-', csicr..cd : dert rcr r.3 :.-.3 s L o.-..a,

.jctuct:o.ns of hc e f :es .a t,-. co-.pos p. n.t. Tr.c tciper:~.-cs .r.

the c:gsrer bui:.ing where t.ne t-aps .'ere located affected the njuber of

fl ies caught d r ing the s_:.....c:- mor.ths and this szu-dy failed in i-s

orisinz. goal. r:c.saver, tns-e c.ta do show a general trea-d during the

cooper m.T.cn-s an: d..ons:ratefd thIt ::'. J.u:.ding design rdJucjd tlhe

number of fl ;es present i -.he di.,st :r building during the p.ricd w-hen

fly r.:.-.bers were ajte.-.:.al. L.'e greatest.

T-.e r.L-:ibe" of flias ca& :, : o.- sticKy' t-pcs placed in the differer.:

ages of cor-post .r, shcha-n in TabLe 10. Thc:. data demonstrate thra

flies prefer the f.-ehly ground refuse. Gretzer th-n 53 pe.-cur. of the

f; .cs in the cigusters r.ormaly congregated in the crea of the 1- crd 2-day-

od c Gpos .





Table 10. Number of adult house flies caught on sticky tapes in different ages of ccnposl..


Percent of total
flies caught in
Days compost in digesters 1-Day old 1+2-Day old
1969 *cek of: 1 2 3 4 5 compost compost

Jan. 12 629 417 434 360 367 28.5 47.4
Jan. 26 266 182 173 91 119 30.8 52.1
Feb. 9 241 150 121 94 105 33.9 55.0
Feb. 23 74 65 44 46 51 26.4 49.6
Mar. 9 28 27 21 36 20 21.1 41.7
Mar. 30 154 130 45 51 12 36.5 67.4
Apr. 20 553 321 123 105 52 47.5 74I.9
May 4 1413 501 193 197 179 56.0 76.9
May 18 501 365 193 154 162 40.I1 65.3
June 1 790 347 228 151 198 46.1 66.3
Jul. 13 99 55 40 26 37 38.5 60.0
Jul. 27 85 106 17 46 32 29.7 66.8
Aug. 10 83 46 45 56 16 34.2 51.8
Aug. 24 176 128 '44 .51 37 36:3 62.6
Scpt. 7 123 116 41 49 79 30.2 58.5
Sept. 21 105 81 69 I4 51 30.4 53.8
Oct. 5 86 134 75 59 88 19.5 50.0
Oct. 19 188 92 91 58 61 38.4 57.2
Nov. 2 407 369 226 201 321 26.7 50.9
Nov.. 16 677 533 675 424 297 26.0 46.5
Nov. 30 971 714 542 407 469 31.4 54.4
Dec. 14I 680 461 437 374 217 31.6 53.1







Evdlut!oon o' F 1, St'c'." Tam .


elet'-.od S

A nc:n nL -ibe." o .'.c 7. .-.e.re -el i.ce a : ,'r-e t. -cc

screen c.a e w :h sticky :tpo s to c--U..."-i.a if ..-e r.u;.'.3r c. f ic; cLu jht

co '.u d be correlated wr.: t.. coazl .-._.-.b .- 7 f : .-, n:. t -.- ;-

..* Is located in a. p rtially s.-..dad c behi. r. tr -.',in bull i-, c- ..,f 3A

Cair,esv:1 e l oora:ory. The c-ce -hd a 5 x 5 .n aasa wi\ a ccc:c rc;-.

rof0 3.5 m high. The floo.- c.ns sted of soil and :..s ukept claearne o.:

-:weds and grasses jdring the tests. T ..cr 1.2 .i~ states were driven intc the

ground on th.. center l ine c,, r.e ca2e 1 r. fra.. ecch end. A s. ...
was hing on eac-. stake ar.d .-'.Lcud dl. A I xi 1.0 x 1 2 c.m ]"-helf

metal stand was p-ccd ;n the c.ntei- cf th.e cage to .hC.d the food .nd

water SLup ed cally and to provide shelter for the flies. Tests were

coidjctec dr ng June: July, and rugust of O069.

Test insects were obtained as pupac from the LSDA's insectic~ .

susceptible !o..ose fly color, and were held in cages until adult files

were beginning to c-nerge. At the onset of eclosion approximately 200

pupa3e were placed i, a 15 x 24 x 27 cm, cuz z ca~. After 24 hr the

rerimining pupas %,ere removed. The cagcc we.- provided daily with fresh

fly food and v-.ater and were held in a roori provided with 16 hr of arti-

ficial daylight by f:;.-escent lamps. Temperature and humidity were

rmaint ined at 26Z ar.d 7C percent Rn.

Flies used in the test were removed frc., tne cages, anesthetized

with carbon dioxide and counted. A 1:1 ratio of males to females was

SE.LCt n. t,. f'. s ;C.e.u Z..en rel Esed nto .ne large cou:door a;'L.

Sticky t.p... .... r-sac :r. .: cjtaco-r co-e iMUnTdadziatly aftar rel(asin3






55

the flies. Twenty-four hr later the tapes were collected and the numbers

of flies counted. All flies remaining in the cage following a test run

were killed using a fly swatter. Pupae, 1-, 3-, and 5-day old house flies

were released in the cage in numbers of 100, 250, 500, 1000, and 2000.

Duplicate tests were conducted for all ages and numbers of flies tested.

Ore-day old flies were released in the outdoor cage 24 hr after

placing the Energing adults in the small cages. This procedure provided

flies which were 1/2 24 hr old at the start of each test. Three-day

old flies had emerged 48-72 hr prior to release and 5-day old flies had

ez erged 56-120 hr prior to release.

In one series of tests, mature pupae were counted and placed in the

large outdoor cage. Sticky tapes were hung on the stakes and 24 hr

later the number of adult flies which had emerged during the test was

determined by counting the number of remaining pupae.

Results

The number of flies caught on sticky tapes was linearly correlated

to the total number of flies present in an outdoor cage as shoan in

Fig. 15. A high degree of correlation was noted for flies of the same

age while there was a smaller though acceptable linear relationship in

the combined values of all ages between number caught and number present.

The slope of the correlation was calculated following the procedures

outl ined in Dixon and Massey (16).

The percentage of flies released as pupae, 1-, 3-, and 5-day old

flies caught on the sticky tapes were 11.9, 24.8, 17.1, and 19.2,

respectively (Fig. 15).'













-----o 1-day old, 24.8% capture

--- 5-day old, 19.2% capture

c--- o 3-day old, 18.1% capture

*----* pupae, 11.9% capture


100 250 500 1000 2000
Number of flies released
Fig. 15. Number of house flies captured on sticky tapes within 24 hr after release in
a large outdoor cage.


600


500
-o



U

1 300


o 200
L.
.0
E
n 100
z







57

The small er n-iber cf fli cs trappec wncr. pLpaZ V.aUs zl lc.-.:c tt

e.arge ini the- otdo r cage ve are 7no surprisir.g s r.ce a highe- mcrtal ity

rate w s expected.



C'e err:in:. 'or. f ..'1 1 r1: r. '.TLr f hI- -icjse Fl1 -, O; d Zt ic.-


'. thods

The total nu,-.,ber of hcuse fI cs in ;-.e digester c'uilc:ng I.;-

est: T.r. ted b/ de:e.m r. in t-ic po -ca- S o r' ked flI :aptP .cd c.-

st cky taes that were rel eas-:s :r. *:a: Z- -c. ...ree-dca old .-...se ..S

fri,-, ;th USDA suscet.:' co' C y :.'ere criesth.at:zed by cac. on r io> d -r.d

placed "..:o small scree- :-.oldinc ca-es. Ti-, e- 'lIes wer e .-arked by

..dd:..g or.e-.a teaspzon of DayC o (Si.zer brot;- rs Ir.c., Cle .-lard,

r,.:o) f;jo,-escert djst to ap. -o.; i.-.T el / 00 ,l i and genzly rotcz inc

t..e cage-s. Tr.e 'lls were c. e. tre:aL er.-ed :o 15 x 2 >. 27 g-uze ca:ee .

Folacwlng a 1-hr period to allc. t:he fl'es to rec'.'rr, the fl es wLere

transzorted to nri- cc'-pos: pian:t .-,d released in zhe digester buiidirg.

A. r'eases were mrri- bet'.-er. U0:00 1 1:00 a cm n a S c-urday or -

S-nday when t.ie plant w-s nort n c erat.cn. Al thugh .il1 the doors ;r.

the c -ilding .wre,-e c!osed, f Ics were not confined to the digester buidir.g

because tne sid.-ng d:d r.ot fiz f:us:h -c the bcse of the bLilding caving

a 25 cm. opening.

The flies w.-re captured by 5 sticky tapcp suspend; d fm .tn tket-s :n

the c;gest.r-. n-d were the si--me as iescr ed previously for :" se.sc-ial

flu c:;ut irn survey. The stick/ t:pcs were collcc.cd 24 hr ;-f:er ccch

rc_ eas. 3.-,0 the rsr--r 1 ': 2 c n i d -' us. C i b-.:ora,, p -,'-r

ui-r ,' ct 1. .:. .o .- rdse- ...-. r.-dc :.-.v lvir.g 1530 -' ic; .-:.:

alnd war, .-.,de i .h 50-0 f is ach.









Results

Ar. v.-erase o. 1.S percent of ,he laoror cor-recrud ho-.- fli e

released in the digcsters %a.are captured on sticky capes ablee 1 ;.

The capture of hose f!ies cn st:cky tape- in a large cutdocr c5- was

s.;o.'-n pr. ioJsl y to b- prop!ryo.a. to .n, ._-o':.-.- o .:l is pretc- r.:.

:.'hi.:ner the percent, c capLurea 17 p rc; r.: as s-c..n ;.or f-c c!

fl ies re:'.ase' it. a out-oor cacg as sho.-.-n .i Fi.. 5o5 o, l.c pec- -.

as sho..n in T7bla 11, 1 .Culd depend on the circJ..s::nces. Ad iteaoy,

any '.lue assigr.nd wojld be questionable due to d-eth, di-parsal, &nc

er.\ i.-on.-ental .actor Hc.-cv- r, in the cres.r.t case t.h- va.ue 1.

percr.: is gIven cred.-.ca since :.ur'vc-h :.id Thagg rdc (-3) counted 1.25

percent. of tie houLc i ies preser.t in a sirr.ilar p rt:iaily open s i:;Jaion.

Ti;s fig-re (l.a pc:cent) can be us.d to estimate the total n.umTer

of house fl es preser.: in :he digestars based on tne numbers cajgh n. on

the LtiC~y tap-s. For example, Fig. 15 sho.-is tha: 48.9 fl ies per stake

per day w.are caS-g.t the aeek of Ap-i! 27, 1939. An estimate of the

tozal number of flies present can be calculated b, ICO percent 1.8

percent x 5 stakes per day x L8.9 fl i s per sLake and is equal to 13,569

hose fl;es per d-y present ii the d:gester building during the weer of

April 27, 19S9.





Recapture of 3-day old markeda laboratory reared house fl ies by sticky tapes hung in
digesters for 2i4 hr following release of flies in the same area at the Gainesville
ccmpost plant during 1969.


No. marked flics
released


No. marked flies
recaptured


1500
1500
1500
1500
5000
5000
5000


Average


Percent
recaptured


. 0
1.8
1.0


2.5
1.7
.8
1.3

1.8


NIo. unmarked
flies trapped
on sticky Lapes


42
30
33
396
1058
696
1i50


aDayGlo fluorescent dust.


Table 11.


Date


Oct. 5
Oct. 12
Oct. 18
Nov. 16
flay 10
MIay 17
Dec. 13















SECTION IV


HOUSE FLY BREEDING IN COMPOST



Observations conducted during 1968 and early 1969 revealed that

house fly larvae were present in the compost in the digesters and

along the conveyor belts where spillage had occurred. The ability of

house flies to breed in compost presented the possibility of great

numbers of flies reproducing in the enormous amounts of compost avail-

able.

An investigation began in April, 1969, to determine the extent and

some of the limiting factors of house fly breeding in compost in order

to devise procedures that may be used to prevent or hamper house fly

breeding.



Moisture and Age of Compost


Methods

Composts of various ages and moisture (%) were evaluated to determine

their effects on house fly breeding. Compost 0, 1, 3, 5, and 10 days of

age was tested at 30, 45, 60, 75, and 90 percent moisture. The age of the

compost was determined by the length of time the compost had been in the

digester. The 0 days of age compost was freshly ground refuse taken off

the conveyor belt just prior to discharge into the digester. Compost 10





61

days of age was tested prior to and after it had passed through the final

grinders.

The samples taken from the digesters were removed from a depth of

30-60 cm and placed into a plastic bag. A minimum of 5 areas were

sampled for each bag. The bag was then sealed and the contents thoroughly

mixed. A 10 gm sample was removed from the bag and the moisture content

determined with a moisture determination balance. The moisture content

of the compost in the digesters usually varied from 35 to 55 percent moisture.

Since this was greater than the lowest moisture content tested, a portion

was removed from the bag and placed into a plastic screen mesh bag. The

mesh bag was then placed in an oven maintained at 800C. After a short

drying period, the compost was transferred to a separate plastic bag. A

10 gm sample was taken to determine the remaining percent moisture.

The desired moisture content was obtained by adding tap water. The

amount of water added was calculated by the following equation:


(y) (100-z)
x = z
(100-y) -

x = ml of water added per 100 gm of compost
y = moisture content desired (%)
z = moisture content of sample (%).

After the amount of water needed for each desired moisture content was

calculated, the compost was divided into 100 gm portions and each portion

placed into a separate plastic bag. Tap water was added in the amounts

calculated and the bags were sealed and the contents mixed. Fifty gm dry

weight samples were removed from the bags and placed into waxed paper cups

(0.946 I) which were marked for identification. Either 100 eggs or 100

48-hr old larvae of :. domestic were added to each cup. The cups were

then covered with black cloth and secured with rubber bands. Temperature








-,0
,nd h-,-;c : y .-rc;e ,r; :ntQ.ain-d -: 2- C -.d 70 p-rccit P.h. Seve.)i cL.y

after e ging or 5 ccys after placing t..e lar'vL. in -:h co-..pS .-e c-ps

were emptied ir.to a p.n of water :nd the cl.-_ting rupa-. '..eri cc'. c:1:

ra d co-.n:ed. Each test -.,s real :ca--d t .--. CS'.A fly r.r .- .

conte:r..r.:g 6 pcrccnt .o:s:u.- w3: uL.LC c ; co. :-o.

Fasul :s

;-'o.s:L:e cointer.t a the- 2: o0. t... C3TpI- -: ha tt-1 -!l.- c:.

,-., ,--turatic.-. of 5-,-.." o d ho-u.-- f y l .-v -t-bl 1] ). .o.*. ,.' r, ..-, e

factors c ; r.-l -..-.ce z.-.e a.eve' co.T. .t o.: hcJU -. c frc". ea. -. 1

ages of co.-pos :e:-,.d co.-nta;.-ing j3 -an 75 perce.-.L mc G;tZL r suppc.":ed

hoLS-e f'y development to .c- e:-.tent. i.ne :.'., p,.-cc.-.t -noistur inhkiIt:d

house fl, cac opT. t w.-. 'e 43 percent macis-rc ,..' Ir.surf :cient :o r.a,-

house flecs. Fo.:y-fi.,a perce-. .To;ctur inr. freshly .round rcfise

resulted i.f lass .tn.a 1 pe-cer.: sur ia\ i to ppaL. It should be r.otec

tha: tnese tests uer, sua acted to a.O ientF.,4 (70:1) and moisture

flLctuat:o.-.s duL in t.e tt-. peroc .-ere not r.:;easure.

The zae of tri ccco-,: f-. dect.d ho-s fly development jut ihis was

secondary to moisture as .hc..n ir. Tab!K 12. There was a s:Snificar.:

reduction ;n tne number of eggs that d-vAlopcd o popae .;n 3-cay o.d

ccrr.pos at cj percentt moisture b.t no significant reductions occurred

in tne ages of ccO.post :estica .t 75 pc-'cent moisture.

.he effects o1f Iac.sture Lr, house Pl dIL'I.!opm-ent friom C s .was extended

to cef ir.e more closely h. o : ir,:u.; r.oisture of co,-post for fly oreecir.g.

In this test series 130 M. dcic-st ic e'gs wierc placed .i 3-day old co,-.-os

co:.tc;n :; S5, 6;, 7a3 c tr, d

c;.T.e -.",'.,,.r .. dc, -C; i ,. . L','e. Jic.- .O.; C ..- ,t vwas r: .." T cac?..C:






Table 12. Influence of moisture and age of compost on maturation of immature house flies reared
in compost.


Time conpostedb Percent moisture
(days) 30 45 60 75 90 Control

No. of pupae collected per 100 larvae (48 hr old)
0 82.5 78.0 84.8 81.6 67.0 94. 1
1 54.3 81.3 58.6 33.5 50.3 92.5
3 84.3 74.3 80.3 88.3 80.1 90.1
5 76.0 80.6 84.6 91.6 70.1 92.6
10 81.6 79.6 86.6 90.3 58.5 92.6
10d 82.8 86.6 89.0 90.5 80.3 92.6
No. of pupae collected per 100 eggs
0 0 0.8 16.5 43.3 5.6 80.6
1 0 0 11.3 33.8 .4 87.6
3 0 0 21.2 40.8 .8 78.6
5 0 0 3.1 39.0 .6 64.8
10 0 0 3.1 25.1 .3 80.5
10 0 0 .3 8.5 0 88.3


Mean of 6 replicates.
Length of time in digesters.
dCSMA fly rearing medium containing 66 percent moisture.
Passed through final grind (finished product).








64

10 times. CSMA fly rearing medium containing 66 percent moisture was

used as a control. The optimum moisture content for house fly develop-

ment was 75 percent (Table 13).



Sludqe and Grinding


Methods

A test similar to the preceding experiments was conducted to deter-

mine what effects the addition of raw sewage sludge and the grinding of

refuse had on house fly development. In these tests either tap water

or sludge (approximately 98 percent moisture) was added to various

grinds of refuse to obtain the desired moisture content. The sludge

was obtained from the storage tank at the compost plant which was main-

tained by the city sewage treatment facility. Sixty and 75 percent

moisture contents were chosen to be tested with the various grinds.

The amounts of water and sludge added to achieve these moistures were

calculated as in the previous study.

Four sizes of refuse particles were evaluated in this study. These

were obtained from refuse taken immediately after primary grinding,

refuse taken after secondary grinding, a 1:1 mixture of refuse from the

primary and secondary grinders, and refuse that had passed through a

small laboratory mill with a 0.63 cm grid. These samples were placed

in plastic bags and mixed with water or sludge in the same manner as

described for the previous experiment.

One hundred M. domestic eggs were added to 50 gm dry weight of the

test materials and placed in waxed paper cups (0.946 1). The cups were

covered and the pupag collected by flotation 7 days later. CSMA fly









Table 13. Influence of moisture on maturation of immature house flies
reared in 3-day old ccmpost.


Percent No. of pupae collected per
moisture 100 eggs

55 14.0
60 21.7
65 23.7
70 30.2
75 39.4
80 21.6
Control b 80.3


Mean of 10 replicates.

bCSMA fly rearing medium containing 66 percent moisture.





rearing medium brought to 66 percent moisture by adding either water or

sludge was used as a control. Six replicates were prepared for each

test.

Results

The addition of raw sewage to compost of all size ranges produced

a higher yield of house fly pupae than the addition of an equal amount of

water as sho.n in Table 14. Such an increase is not surprising since the

total organic content was increased and since Olson and Dahms (49) found

se.rage sludge an ideal breeding medium for house flies.

The effects of grinding compost were not clearly demonstrated. The

results shown in Tables 12 and 14 indicate that the larger particles were

more conducive to house fly survival. However, the size of the refuse






Table 14. Influence of sludge and grinding a of refuse on maturation of immature house flies reared
in compost,




50:50 Mixture Refuse after Refuse
Refuse after of refuse from secondary passed
Percent primary grinding primary and grinding through
Moisture ca. 8." x 811 s econ da ry m ilIls ca. 411 x lif ]/A" gridb

a. Water added for desired moisture controlf = 85.2).

60 26.3 20.5 19.0 0
75 33.6 29.1 30.0 0

b. Sludge added for desired moisture controlc =8.)
60 31.9 26.3 28.0 2.8
75 47.o 39.5 35.3 19.8


aGrinding samples taken from grinding millIs at the Gainesvill e coiipost plant operating under
normal conditions.

bRefuse from secondary grinding mill passed through a small laboratory mill.

cCSMA fly rearing medium containing 66 percent moisture.





67

particles varied '..i :h r.e daily \-. ar of -.he grinding m:ils and the exact

size r-nge CL1s difficui: to ascert:. n.







The terTp, r.-'z urL s ocx-.'i:'g :.-.c .. / ra.rinr con. incrs J.;

:inves:igczed to c ter.T;nc tiC t n:,r-t.-r.r .-;-', rf -r.e2 b ir,.-.L.

I.'IuO se J : l as i .ne pr - "-. A "k ..A 51. -:I s i co cL c:... .T. -..

(Atkins Inc., C ..'.svy .1 : .? or. c ) .e.- p acec i;. 1i0 1 ic :.-ea.- n;

tu.. ,c.'. :.z. -,: ;.-.g .:'. :-.c -.: "f:'/ ,' r ": rc : .;: ,.:,. : ,o,? '.-e:.." .': .c."s .:"

,."t p'cb:,es w e e.- p, c cc '. t ...;:, 'i ic... c :,e ..:~ ,. e.' .- a r,--, i tc

The t. .i:,e. -jr ,,.:,- .- : .---:.J c.e r, _. :-,.- for,.- J '-ys. 'c'.-. -

waZs rc l i ca: d 3 t i... L-

The mian ..T. -raLure recorcea ; the -'earing tubs at each pcsiticn

are oreser.tefd i.-. TZbL'e 15. T.-,I b! cckc: cat.- ;r. T b. e 15 reprcsenrt

those probes i. areas OccLpied by ia.-rv.e. The mcx mum tczrm.perat-e

observed :." :;-.e larval region b..s L6.1 C. "."t se data indicate that larvae

develc, :.n a tem.perture range of 23 S-.SJ C.

The .c.-.:i.:.un tc.- era. re in whic.i i a.',ature hojse fl ie. can develop

is not kno..an. T.ere are ma:ny rdfercnces deal ing :Wi tenperazure studies

c.i house flies bu : uite defi:. te info.rmiatiron -.'s found concer.ing this

pa.-ticuLr area. Jest (32) sttcCed tht h-cuse fly eggs car.not su..'vive

a temperature tcove ".. l1C while F.c:bajd (59) repor:cd the: larvae died

in 3 minutes when exposed to SJ L.

Tc determ..-.e if zh- temT.erat_.-es tzcir.cd i., ..c d.d -s- -s 7..'y

tre.c.t hojse ,1' d vele;.:..:. :. t c cCT.o .t r. A.:i.-. H 51-. s.;:. co-d. ctc

t.n-.-..c.LA.cr '.;s CSL '' reton e ur. L.'-. e .-T-c.'- .L res. -.'. protes v.ro






















level of
med ium
1 2. 3 1 2


5




10
sponge86





-7.5


30





F ig. 16. Pos it ion of temperature probes in house f ly rear ing
containers (distances in cm).






1Tbl I T1.. Tcni pr.ltur:s oLscrv'cd iin iho".e 1 *, ri rin cci ita incls.


Decgres Cent iqrcadI rccci dcd b d,s aIfLI r

i" r 1 2 -3 I; r 6

1 3I:.9 35. 7 33.9 3C.3 31. 1.
1i0.7 1.9 37.8 33.6 33.3 29.':
3 I6.3 i 2.7 37. 2 32. 3:.8 8. 1
.; ..8 1 .4 /:3.7 37.i' .... 9 3i.0
r 1"3, 2 1: 9 1:1.7 36..7 35. E. 32.,


7 I5.8 C i9.' ':,4. 1 3 0 36. 3 .5
37.1 39,2 3 2 37.0 3'.1 33,2
347 36.1 31 31:. 37 4. 2 .0


SL ricj 1 2.

IL, In of 3 rcpl icatc.s recorded by, an Atl :ri's sc ij con.rlu- icr tliheiiOncLtcr.
CBlockcd data ii..'icate area oLCLIpied b ,' lrvie.






70

placed in 4-day old ccr.post at depths ranging from 1.27 15.24 cm and

alloIed 10 minutes to equilibrate. The temperatures were then read and

recorded. Twenty-five readings were made at each depth over a period of

several weeks. The temperatures ranged from a mean of 38.20C at a depth

of 1.27 cm to a mean of 59.4 C at 15.24 cm (Table 16). Information on

the temperature in the digesters at greater depths was supplied to the

author by Dr. D. T. Knuth, Environmental Engineering, Inc., Gainesville,

Florida, and is presented in Appendix 4. From these data it can be

concluded that temperature would prevent house fly breeding in the

digester except in the top 2.5 cm of the compost.







Table 16. Temperatures observed in 4-day old compost in digesters.


Depth (cm)


I 5. 24
12. 70
10. 16
7.62
5.08
2.54
1. 27


M i n imum


56. 2
54.3
54.7
48. 4
43.0
40.0
35.8


Degrccs Centigrade
Maax imum


61.5
62.5
59.9
59.7
55.5
66.0
62.5


Mean of 25 Observations


59. 4
58.5
57. 2
53.9
'9. 7
44.9
38. 2


Sewa e sludge added to achieve 50-55'. moisture content in compost and ca. 1.6 ft per hour of
air per ft- of refuse suJppl ied for aeration.


Neno 2 berain
















SECTION V


MIGRATION AND DISPERSAL



Compost plants and other similar types of refuse handling systems

are centrally located to lower the transportation costs. These facilities

are optimally designed to operate in these central locations without

causing a nuisance to the surrounding community. The Gainesville compost

plant has previously been shown to produce approximately one-half million

adult flies per week during the summer months. These flies may disperse

into the surrounding community, thus discounting the value of central

location. An investigation to determine the extent of fly dispersal

from the compost plant was begun in 1969. When the plant closed in

December, 1969, these dispersal studies were completed at the city land-

f ill.



Literature Review


House Flies

There is an undue prominence often attached to the maximum distance

of dispersal of flies (63). Flies released from a central location and

recaptured later at some distance in very limited numbers imply that the

area covered is subject to infestation from the release point. Although

this may be true, it should be noted that those one or two flies





73

rccovarea at some -reat distnr.ce %..ere Xonr thre xcti io.na fe. zat, b,

soe ] c-ient oa c.iaecE, rraqad to Lca. v'e this is -ance. Th: d scE.-al

of th the of the f / pop-'~c.' 7- rat:.e.: zrn.-i that of -- fe. ind v cu:.

is the s i r. ic .'.; cri:e i.- C., o ." a c.:e. Z. .zc rd : n -.*: c:. -. S..'.

(63). T:- d.?p-e:. .l c p::!t' c ..:. i,-s c:p. ctiorn is c :, ;p cec be

ex e., dcd \w::;r.in '/2 2 mi z ccuse o.: -he a:.-;2:..-..g c.-.:r:.- c

hoLSe fl.y rovZT,.-It ( :, 7.E, 5;, 5 6, 6;, SL 75). -T :", m.O/.s f:c.- c-.

;ield of a s:imulurr s c--aus! r.3 a .-opic zaa: :.o. or :, at f cr.oth (3,'.

A fly r..ac/ travel 15 n1 es to r.ch a c s rce I ile :-o it- orig.n (6l).

The attr-ctiveness of the r lease s te may greatly irnflue nce c.spersJ.

Picker.s et a'. (51) recap:uired 1 percent of the liberated house flie

z the .e ezec sit .he...'rr.. r. z:. ., k. a:.

fl ies in an, open area loccrcd at :..e center of a 1 '2 mile circle of L

carns only I..1 pe.rc.in of t..ese fiies were recapTu.-ed. Schoof (63) four.d

that ir. rr. r.y instarn cs flies dispars-d from a location despite tre

presence o n.r. apparent exce-ss oi feeding ar.d breeding areas.

Tnere ae- cCni l ic:;r.g reports of the effects of i o u n rly cIspersal

(25, 40, 52). H.o.-.ever, -he nore com.iiireer.s ive studies of Schoof and

Silverl y (64) four.d th.- ncusu fly movement w.'as not equal in magn;itud in

all directions arnd Pcke.isert c'. (51) r:./alod that fly aispercsl was

ra.-,dc- wner, the w':nc w/as variable and -upw.n:d t.h-n the wind blo.- pre-

cAT, inantl'.' from 1 quartc.-.

C',ata et :1. (.6) demonstrated that hoJse fly d:spersal w.'as not

influenc,- .y hi;n.-iays, rice fields, or rounr air.s. Dispersal is influenced

by tre a;c. snJ : ..; Ti of :h ," .: .,.r, :hc.- no sc."r, i c.-t c '.c..

c,;,.--/ .a ;r. "... .:; : .. .. .. -.:. c ,- .' .., : 2, . f .





74

Schoof and Silverly (64) concludLd :t;t the cc-.non characteristic of

fly d ipoars:,l was a bS'ic rdr.dcannss of movement ir. flucr.ced by 5 conditions:

i1) popLlat;on pressure, (2) differentially attract ..e site-, (1) geographical

barriers, (4) preferen i:i r.ovenent, c. (5) ir..ijrn:t tcncency of fl ies

to disperse.

.he rrA;m...m ".g.'it r.-ang c i. ;- ccorccd i .- ,o L Js di W,

usually :e r.axirc.J d :st-ice of trp??w ng. Tne nzximur. recorded fl;gnt

of no a. flies is 23 miles (S3,.

E1 o. F ies

C:imor- a (2.) f .d t' .a: z . P .- ,-'ael a.d at ce-.tral point

.cre distr;ib5cd .-cndc;nly after 2 Jc/s in open sheep country. MacLcod

c-.d c.-.r-.ey ( 3, 3 ) co.-,clu-e tn:: bhc' f y cispersal was r ar dor-. Lt

:;,o acscreg3aticns .c.-e fc.-...e p.odLcing a clbmpcd distribution. These

qgg-eCgz .ons ".erLe dJ to aiffe-ent d gra3.s of attraction offer&, to tncse

indivic;a;s ir, tne:r ra.dc.n :.iov rt acro-.s the activity, arcs. These

a:t.ncrs later occided on two types of blo: fly 1 i'"t: a sustained

cispersa; flight, ir.d>pende.: of the enviro-tent, and an i.-terspersal

l :.ght wh::h may :r.voiv n n no r dis l ccc..er.t (40).

GLrnr.y neo .-oc:h: 1.2) .crnd :hat J. cjpr'.na tended to fly da n or

across a p.-Lvc.ilir.g \.'r.d, while Maccod ar.c Donnelly (40) found no evidence

of wi.nd affecting bl -. fly f ight. ",laenicia spp. has dcTons.rat: d a

seasonal n;g.-aL:oi in autumn from the forest to the cities in F;nlzr,d

47) '-r.. f.-0n tr.c forest to opL.n ter. c in .. i G-.;at Britain (36). Pn: menicia

spp. w:s ,nffiLct:Ld oy step slopes of a val ey ;n upllnd Lheeo cCntry

of Grat ;r;c;in t37) ar.c crossec a C;O-y;rv-w la rive,r jnd a SO-ytrd-wide

c c : .-c s.. : 5 -., .-. o-. d tna: b i fl;iess did not fly

during3 hevy ca c- i.-.c -.. =.- -. ; Jir'r i was ,.n aJ i- in daily









active' ity irn .tr a. P. c cr '-. .cs bir:::-. in JZ an, re..-,g ;,cs

n rero s In h e aft -rr c pc-l. : 7'4). Ii:n- a .:" s recorded -.7. -

fr -i : c r ib.cr a: s' : -.!.: i : .- r .).

CcToprehe.ns i'e r.v : .'s o. refcrc- as on f!l.. .'. oispeirs:1 zna

.migration a.e presar.ted b5 JC-.r..c-. - .. .. r r ).



-1] -r "l' I


Fl ight mill s :rcv';de a C:-.r. ni ui m.cr.. of' c sj....': n c:. ac:e.' .7 :s

of .r.sac. l g-.t L.:.J .- conc"ro i e..vi.c.T....;al c d. 0.s. S ir.:e ?

CuL r..-z '..-s crc f.-c.A..:.f.: .: ',, s -i3 a: ..ne coZ posz p 3 li o.-.:c.,/-

reared spc.me:..._ E.,ro a :..c tC o fV'g .t m t aarT.r.e tn i m:x;
disC.:r.c they ,my LC; V ir. d :spers' fl ich:z.

A ;.mp l ccr.s ruLcrt-c f!i t ri' i i as .s.- by .tk ir.s (3) -.' th the

sco.yt id, Dar. -.cc:cnus pFse. :o s e lc. <. .?.is de. e ,.a .as imy,3-,v J

Sr.i;lh -ad Furn:ss (77) ar.d Rc. le,' .: (CD) by ato.Tiacically recording

th- re. iutiorns of t..e mills by ,-.eans of p..D:onelectr.c ce', s and -l ctr.ic

co. ters. Chcrbers and G'Conncl (1-2) furznsr improve' ths e c ic._e by

reduL.Cng t.ne f:Icoc.' of ,ohe ..i .ls ty suppcrt.:n, the pivot bSarzc..-. 2

rr.,gr, ers.

t- enc-s

ThI f. 'gh. mi I s s,.d ir. .'.. scud. ,'ae an-rc-o'ly p.o'.-idod by

Dr. .. L. Eaiiy, JSA, Ga.'n sv;i; Tnr .-c, c-rs of hecs.e ill u.-.,e

cz. s, zruc J frz .i 0.5f r-..: c-,r o. :i- s;tcn 1 r. 1" c :n nC.1 tn, n eand or

this wi .-e w.a ban: : .to 2 r :gCt a.-rl as sh -i.n n F'g. i7, so t.ac. zir.

ze..T.. -, 1 r.. oc" th. '..'. r ..- er.cnc :- 1 S r t .. c." .... .- o."

c-r.~i. 0 3 an l <-.'. .1 o" 1" \.' rs ^.r.rt "i L. :.. :::;... .,- 1.-..i as:-^ ..a






76

the end of the rotor arm to produce the double end shoxvn in Fig. 17. A

pivot was fastened 16 cm from the end of the arm so that the circle it

described had a c;rcumfrence of I m. The pivot was a No. 0 insect pin

with its head removed which was glued, point upward, to the rotor arm

between two 6 cm circles of paper. The pivot was suspended between two

6 x 25 mm magnets (stirring bars) so that the pin was in contact with

the upper of the 2 magnets and was stabilized by the laoer magnet. The

magnets were supported by 2 wooden doaels connected to a steel rod frame.

The revolutions of the arm were counted and recorded by a method

similar to that described by Smith and Furniss (77). A 6 volt lamp was

attached to the wooden daoel holding the laver magnet as shoan in Fig. 17.

A photoelectric cell was positioned above the lamp so that a 2.54 cm

black paper disc glued on the rotor arm would interupt the beam of light

with each revolution of the arm. This paper disc was 7 cm from the pivot

on the short end of the rotor arm and also functioned as a counterbalance.

The photoelectric cell was connected to a poaer unit which operated an

electric counter.

Flies used in this study were reared on a diet of lean ground beef

in the method described previously. The flies were anesthetized in a cold

room maintained at 2-40C. These flies were then attached to the radius

of the mill with a drop of rubber cement on their pronotum. The rotors

were then immediately mounted on the mills. In one series of tests,

P. cuprina of various ages were placed in constant light provided by

fluorescent lamps for 24 hr and the distances flown recorded. Ten male

and 10 female flies were used for each test.

A second test involved 10 male and 10 female P. cuprina which were

attached to the rotor arm approximately 4 hr after they emerged as adults.









































Fig. 17. Diagram of insect flight mill. a-rotor arm; b-magnet;
c-counter-balance; d-light source; 3-photoelectric cell; f-metal
plate; g-cotton ball.







78

These insects were allayed to fly until death. The flies were allowed

to fly from 8:00 am to 6:00 pm each day under constant light. In the

evening, the rotor arm was fastened to a magnet placed on the metal plate

as shown in Fig.17, and the flies were allowed to feed on a cotton ball

saturated with a 10 percent sugar solution. The lights were turned off

and the flies remained in this position overnight. All tests were

conducted at the USDA laboratory in a room where temperature and humidity

were maintained at 26 C and 70 percent RH.

Results

The mean distances floa n by various ages of P. cuprina attached

to a flight mill for 24 hr are presented in Table 17. The greatest

distance travelled by an individual male was accomplished by a 5-day

old fly that flew 24,129 m. The greatest distance travelled by an

individual female was 19,603 m by a 3-day old fly.

Male and female P. cuprina flew an average of 19,405.4 m and

25,235.2 m and a maximum of 30,127 m and 45,030 m respectively, when

attached to a flight mill until death, as shaown in Table 18. Assuming

these were less than ideal conditions, flies in the field could be

expected to travel these distances and further, especially when taking

advantage of the winds.



Bla Flies Released at Compost Plant


Methods

Four releases of wild flies were conducted at the compost plant

during September, 1S69, to determine their dispersal patterns in this








Table 17. Mean distancesaflown in 24 hr by adult Phaenicia cuprina
attached to an insect flight mill.


Age of fly Males Females
(Days) Meters (Miles) Meters (Miles)


1/2 3,671 (2.28) 2,914 (1.81)
1 8,356 (5.19) 7,725 (4.82;
2 11,335 (7.04) 10,168 (6.32)
3 6,341 (3.94) 8,289 (5.15)
4 5,559 (3.45) 10,776 (6.70)
5 10,273 (6.38) 11,438 (7.11)
6 5,556 (3.45) 7,785 (4.84)
7 5,476 (3.40) 7,849 (4.88)


aMean of 10 repl icates.






area. The wild flies were captured by sweep net from the grassy areas

surrounding the cocnpost plant and placed into a large plastic bag. They

were immediately anesthetized by carbon dioxide supplied fro-n a portable

lecture bottle. One teaspoon of DayGlo fluorescent dust was placed in

the bag and the flies were marked by gently rotating the bag. The flies

were volumetrically counted by pouring them into a 50 ml beaker. This

volume represented approximately 500 flies. The flies were then placed

into gauze cages, alloa.ed 1 hr to recover, and then transported to the

release site. Two releases of 1000 flies each were made at the compost

plant, and 2 releases involving 1500 flies each were liberated at the city

animal shelter. The flies were captured around 9:30 pm and releases were

made about 11:00 pm that same night.










Table 18.


Distance flown until death by adult Phaenicia cuprina attached
to an insect flight mill.


Females Males
Age of Insect Age of Insect
Meters (Miles) At Death (Days) Meters (Miles) At Death (Days)


26,651
16,931
13,283
15,445
45,030
23,386
26,195
13,994
25,599
40,838

X = 25,235.2


(16.6)
(10.5)
( 8.3)
( 9.6)
(28.0)
(14.8)
(16.3)
(1 .3)8)
(15.9)
(25.4)

(15.7)


5
3


4
6
8
9
9
7
7

x 6. 1


29,546
19,892
16,601
6,477
23,658
30,127
21,698
14,361
9,1 26
22,568

x = 19,405.4


A sample of approximately 200 marked flies was taken from each

release and identified. Greater than 99 percent of these flies were

P. cuprina.

The marked fl ies were recaptured by sweep net after they were

identified by examining the blaw fly roosting areas surrounding the

compost plant with a portable battery powered ultraviolet light. Baited

cone traps, described previously, were placed behind the receiving building,

at the city animal shelter, and in the backyard of an apartment 200 m east

of the plant. These traps were checked every 24 hr for 4 days after


(18.4)
(12.4)
(10.3)
( 4.0)
(14.7)
(18.7)
(13.5)
( 8.9)
( 5.6)
(14.0)

(12.1)


5
4


5
3
5
5
3
4

S= 4.0







each release. The trap at the animal shelter was removed for those

releases at that location.

Results

An average of 10.7 percent of the blao flies released at the compost

plant were recaptured in the same area 24 hr after liberation as sho.n

in Table 19. Traps baited with i-day old fish heads at the city animal

shelter and behind the apartment failed to capture any marked flies for

these 2 releases. Flies released at the city animal shelter were

recaptured at the compost plant at an average of 5.65 percent. The trap

behind the apartment failed to trap any marked flies in these releases.



Fly Releases at the City Landfill


The compost plant closed December, 1969, forcing the completion

of the dispersal studies to be conducted at the city landfill. The

landfill presented a situation different from the compost plant but

similar in the large amounts of attractive materials present and the

generation of a large number of flies. It was concluded that dispersal

patterns observed in this area may be interpolated as to general trends

which may be applied to the compost plant.

Location of City Landfill

The landfill was located on a 30-acre tract of land north of the

Gainesville Municipal Airport. This area was surrounded by pine flat-

woods and the closest residence was located 1.2 mi south of the landfill.

The Gainesville Industrial Park was located I mi west of the landfill

and the airport runways began 1/2 mile southwest of the landfill. Three

residences were located 1.5 mi north of the landfill while woodlands

extended for several miles to the east.









Table 19. Recapture of wild marked flies by sweep net and baited traps 24 hr after release.


J1o. marked flies INo. recaptured Percent
Date Release site released at compost plant recaptured

9/11/69 Conpost plant 1000 121 12.1

9/1I/69 Conpost plant 1000 93 9.3

9/17/69 City animal shelter 1500 102 6.8

9/21/69 City animal shelter 1500 67 4.5


DayGlo fluorescent dust.

>99 percent P, cuprina.








Operation of the Landfill

The refuse was brought to the landfill by truck and dumped into

trenches 15 m wide and 5 m deep. A bulldozer was supposed to crush and

pack the refuse into the trenches and then cover it with soil at the

end of the day. Such an operation would be in ccipl iance with the

standards of the American Public -lorks Association for the operation of

a sanitary landfill (1). Unfortunately these procedures were seldcn

co-plied with because of equipment failures. Refuse was observed to

remain uncovered for several days on many occasions.

A separate area of the landfill was used to dispose of dead animals

and the maintenance of this area was poor. Too frequently animals were

not coTpletely covered with soil or else not covered at all for several

days. This resulted in large numbers of flies developing in this area

(Fig. 18).

Fly Behavior Patterns Observed at the Landfill

Before a general discussion of the releases can be undertaken some

observations concerning fly behavior at the landfill should be reported.

Blow flies and house flies were inactive at night, roosting on the

refuse or on vegetation surrounding the refuse until sunrise (Fig. 19

and 20). As the roosting sites were exposed to the sun the flies crawled

about the plant or refuse to position themselves in direct light where

they groomed themselves for 15-90 minutes. The flies then left the

roosting sites, flying as it seemed, an orientation flight. These flights

occurred in all directions, with the majority of the flies finally appearing

at a sunny, sandy area, absent of vegetation. The sunny sides of the

mounds of sand used to cover the refuse were preferred sites. The flies































Fig. 18. Fly larvae in animal disposal area of city landfill.


Fig. 19. P. cuprina roosting on grass tassel at night at city
landfill.
































Fig. 20. Predominantly M. domestic roosting on weed at night at
city landfill.


I


Fig. 21. Predominantly C. macellaria with some M. domestic roosting
on dead brush in refuse at night at city landfill.















sites. House flIies and P. cupr i_,a were both observed to f ol Iow th is

pattern and both occurred in the s;,me mating area s simultaneously.

The roosting sites were centered around the most recently dumped

refuse. M. domestic rested on the refuse, especially brush in the

refuse, and on the surrounding vegetation immediately adjacent to the

refuse. There appeared to be little selection of plant species chosen

as resting sites but there was a preference of height. House flies

appeared most often on plants 1/2 I m in height, House flies have

previously been reported to roost preferably on ceilings, trees, and

shrubs in rural areas (2, 33, 41).

Cochliomyia macellaria were observed to roost on leafless or dead

branches 1-3 m in height. Brush in the refuse and plants immediately

next to the refuse were preferred (Fig. 21).

P. cuorina was seldom observed roosting on the refuse and rested

almost exclusively in grasses and weeds up to I m in height. Green (22)

and Maier et al. (41) observed similar behavior at a slaughterhouse as

well as in urban areas. These flies roosted at a greater distance from,

the refuse than did the house flies. If one walked from the refuse

through the surrounding vegetation, he would first pass through a belt

2-5 m wide of plants containing roosting house flies. This zone would

give way to a mixture of house flies and bcloq flies and finally to an

area where the blow flies were in the majority. The number of flies

decreased rapidly with increasing GistGriCe from the refuse. Flies became

relatively scarce after about 20 m.




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