Insects in relation to national defense


Material Information

Insects in relation to national defense
Series Title:
Its Circular no. 1-23. Feb. 1941-Jan. 1944
Added title page title:
Insects in relation to national defense, circular
Physical Description:
24 nos. in 1 v. : ill., photos., map, plans, diagrs. ; 23 cm.
United States -- Bureau of Entomology and Plant Quarantine
U.S. Govt. Print. Off.
Place of Publication:
Publication Date:


Subjects / Keywords:
Beneficial insects   ( lcsh )
Insect pests   ( lcsh )
Insecticides   ( lcsh )
Fumigation   ( lcsh )
World War, 1939-1945 -- Health aspects   ( lcsh )
serial   ( sobekcm )
non-fiction   ( marcgt )


General Note:
Reproduced from type-written copy.
General Note:
Includes bibliographical references.

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Source Institution:
University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029081698
oclc - 09471812
lcc - SB931 .U44
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Full Text






Circular 8


June 1941






Circular 8 Flies

Table of Contents

Introduction..........................** *** ****
The Housefly..........................
Life History and Habits.............
Prevention of Housefly Breeding...
Manure disposal.................
Chemical treatment of manure....
Care and disposal of garbage....
Sewage disposal.................
Protection of Commissaries, Kitche
Mess Halls, and Quarters from Fl
Screening..... ..................
Fans and electrocutors..........
Fly traps.......................



* 0 0



* *

Sprays. ................
Fly poisons, fly papers, and swatters...
Blowflies and Screwworms
Blowfly Maggots in the Treatment of Disease.
Breeding Places and Habits...............
Control.. .. .. ... .. .. .. ... .. .. .. ... .. . .
Disposal of Dead Animals..................
Garbage Disposal............ ..........
Traps.g. .D..p . . . . . . . . . . . .. ..

Treatment of Screwworm Infestations.......**
Human Bot Infestations......................**
The Human Bot...............................
Prevention and Treatment***............*****....**




Circular 8 Flies 2


The Eye Gnats.............................. 21
Breeding Places.......................... 22
Control............................ ....... 22
Blood-Sucking Flies........................ 24
Horse Flies and DeerFlies............... 25
Buffalo Gnats, or Black Flies............. 26
Sand Flies,or Punkies.................... 27
Biology.... .... ... .... .. . .. .. ... .. .. 29
Control.. ... .... ..... ....... .... ... ... 29
Stable Flies, or DogFlies............... 31
References...... .............. .. ...........* 32


Flies of several species carry a number
of diseases dangerous to man and animals, cer-
tain other species constitute only an annoyance.
The maggots of others invade wounds or the ali-
mentary and urinogenital tracts. The different
kinds which directly affect man may be divided
roughly into two groups--the biting, or blood-
sucking forms, and the non-biting ones. The bit-
ing flies may be very annoying and may occasion-
ally transmit such diseases as anthrax and tular-
emia; however, the non-biting flies, of which the
housefly is a typical example, are of greater
importance because they carry organisms that cause
diseases-such as typhoid, dysentery, and diarrhea
--or the eggs and younger stages of parasitic
worms. Certain species of flies are treated in
separate circulars (see Circular 16, Horsebots;
Circular 17, Stable Flies; and Circular 18, Screw-


The housefly, Fig. 1, easily takes first
rank among the non-biting flies because of its

Circular 8 Flies

great disease-carrying potentialities, its abun-
dance, and its wide distribution.

The whitish elong-
|ate eggs, Fig. 2, are laid
in masses on the breeding
\ media. They hatch in 12
Vto 24 hours, and the mag-
gots, or larvae, Fig. 3,
A feed on the material on
which the eggs were laid,
*reaching full size (about
/ I^^ 2/3 of an inch long) in
/ from 4 days to several
weeks, depending on tem-
i 'perature. 'WVhen full-
/ i V A grown they move away
/ I from the moist parts of
/ \ the breeding material
| until they reach compar-
S. atively dry quarters.
These may be in the outer
portions of the breeding
material or in the soil
Figure 1- The common or debris nearby. Here
housefly, female, they pupate, and from the
barrel-shaped reddish
brown puparia, Fig. 4, the adults emerge in 3 to 6
days in summer. The adult flies expand their wings
until fully developed and dry, and usually move
about and feed for 3 to 4 days prior to mating and
egg laying.
In the region of Washington, D. C. individual
female houseflies during a normal lifetime in summer
of 2 to 12 weeks, deposit 2 to 4 egg masses, each
containing on the average about 130 eggs. In Panama
a single fly has been recorded as depositing 2,367
eggs in 21 batches.

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Figure 2 Eggs of housefly.

Figure 3 Housefly maggots, or larvae.

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Flies probably do not
1 travel far if food is abundant;
However, it has been shown in
experiments that they may travel
as far as 13 miles from the
point of liberation. As adults
jthe flies take food for the most
part in liquid form, but flies
can ingest minute objects and
are known to ingest eggs of
parasitic worms.

Figure 4 Housefly
pupae, or "sleepers."


Because of diverse habits and the wide
variety of conditions under which they breed, there
is no single line of attack which will insure last-
ing protection from houseflies. It is necessary
to use several methods of combating this insect
enemy to secure a modicum of success. The most
important of these are measures designed to pre-
vent fly breeding.

Prevention of Housefly Breeding

Manure disposal.--Manure, particularly that
of horses and hogs, constitutes one of the princi-
pal breeding media of houseflies. Eggs are often
laid on manure immediately after it is voided; all
manure therefore should be considered as infested.
Although large accumulations of manure are most
productive of flies, soil contaminated with manure
and urine may breed considerable numbers. This
makes imperative the thorough daily cleaning of

Circular 8 Flies

stables and the soil along picket lines. Flies
do not breed to any extent in well rotted manure.
It is only during the period of fermentation that
they are attracted to it for egg laying.

Where practical, the manure should be hauled
away every third day and spread out thinly over
fields. This dries it out quickly and kills the
fly eggs and larvae contained in it.

Incineration is also an effective way of
disposing of both manure and immature stages of
the fly, if facilities are available for its
practice, but of course valuable fertilizing mater-
ial is thus destroyed.

In the case of a small number of horses,
the manure may be temporarily stored in manure
bins or pits. These should be as nearly fly tight
as possible and should be fitted on top with coni-
cal fly traps to capture those flies that emerge.
A horse produces about 10 pounds of manure a day
where bedding is not used.

The large amounts of manure produced at re-
mount stations are most satisfactorily handled by
the ricking method of which there are several dif-
ferent modifications. All operate on the same
principle, however. The simplest is to dump the
manure in ricks about 8 feet wide and as long as
necessary to accommodate the manure produced.
The ricks should be short enough so that the entire
surface will receive additional layers everyday
or two. It is essential that the material be com-
pacted and that the sides of the ricks be kept
nearly vertical. To accomplish this it is neces-
sary to use care in dumping each load and to dis-
tribute it by hand.

The heat generated in the compacted rick
either kills the fly larvae or drives them to the
surface. There they may be killed by sprinkling

Circular 8 Flies

the sides and the top of the finished rick with
borax solution (see page 8) or with crude oil.
The heat generated in the ricks can be made effec-
tive against a larger percentage of the larvae
and eggs if the ricks are covered for a few days
after they are completed with old tarpaulins or
large sheets of tarred burlap.


In the more permanent camps concrete bases
advisable upon which to rick the manure, Fig.
These may be of solid concrete with concrete

~ ~ -~ %.-%-- _____

Figure 5 Concrete base on which to rick manure.

trenches around the ricks, or the concrete may
be limited to the trenches. After a rick is com-
plete, a few inches of water should be put in the
adjacent trenches. The larvae fall into these
as they crawl out of the manure and are drowned.
The addition of a heavy film of crankcase oil on
the water aids in destroying the larvae.

Circular 8 Flies

Chemical treatment of manure.-Considering
cost and effectiveness, borax is the most satis-
factory material for use in treating manure to pre-
vent fly breeding. It may be applied as a powder
in rainy climates and in moist places. Under other
circumstances it should be dissolved in water at
the rate of 1 pound per. gallon and sprinkled over
the surface. When borax is used at the rate of
10 ounces per 10 bushels of manure, practically
all fly larvae and their eggs are killed, and the
manure is not injured for fertilizing the soil
to promote growth of most of the crops ordinarily
grown. Some plants are damaged if amounts of
borax in excess of the above are applied, or if
the manure is used in excess of 15 tons per acre.

Care and disposal of garbage.--Fermenting
and neglected garbage furnishes an excellent med-
ium for fly breeding. To prevent such breeding
every kitchen should be well equipped with a suf-
ficient number of covered garbage cans to take
care of the daily output.

Garbage containers must be kept tightly
covered. They should be thoroughly cleaned with
hot water and a cleaning compound such as lye
as soon as they are emptied. The containers should
be conveniently placed, but should be at least
10 feet from the door. Elevated platforms to
accommodate the cans are desirable for convenience
and to protect the garbage from dogs, rats, and
ants. The supports of the platform should be pro-
vided with oil cups or ant tape to exclude ants
(Circular 15).

It is advisable to pick up the filled cans
and replace them with clean ones, taking the filled
cans to a central place for emptying.

Circular 8 Flies

The destruction of garbage by burning is
the most sanitary method of disposing of it.
The obnoxious odors produced by this method are
a serious drawback. The odors may be reduced to
a minimnium by the use of a closed incinerator pro-
vided with a suitable stack. Temperatures of at
least 1250 F. must be maintained to decompose
the malodorous gases. Unfortunately, the instal-
lation of closed incinerators is expensive, cost-
ing about $1,000 per unit ton capacity, and their
use by small units is therefore not practical.

As emergency installations, open incinera-
tors may be used, but they do not burn the gases
and eliminate odors, and are therefore objection-
able, especially if located near the camp or near
towns. Semi-closed incinerators have low stacks
and may be constructed of ordinary brick.

It is often economical to dispose of gar-
bage under contract to hog feeders. Such contracts
should require (1) daily removal of garbage, (2)
the use of clean trucks, (3) suitable sanitation
at the feeding end which should be located satis-
factorily both with reference to the camp and
civilian communities. The production of flies
in an unsanitary hog-feeding establishment is so
great that any military or civilian units within
several miles may be heavily infested. At best,
some fly breeding is likely to occur when garbage
is being fed, and as pointed out, flies are capable
of traveling several miles. Such plants should
be located at least 2 miles from a cantonment.

Garbage, if kept well protected from flies
in cans may be satisfactorily disposed of by burial.
It should be emptied from the cans into trenches
2 to 3 feet deep, or in pits. As a section of
the trench is filled, it should be sprayed with

Circular 8 Flies

crude oil, or better, dusted with borax and promptly
covered to prevent fly breeding.

Latrines.--Sinece flies breed in and feed
upon human excreta, and since the danger of disease
organisms being carried by flies that have access
to such materials exists, it is extremely impor-
tant that flies be excluded from latrines. In
temporary camps this is not easy. Trench latrines
are usually employed in such camps, and flies can-
not readily be excluded from them. The prompt
covering of the feces with earth by each man tends
to exclude the flies, and the free use of crude
petroleum or used crankcase oil repels flies to
some extent and prevents fly breeding. When the
trench is filled to within 1 foot of the top, it
should be well sprayed with crude oil or heavily
dusted with borax and filled with clean earth.
Pit or bored latrines, as used in more permanent
camps, may be fitted' with standard latrine boxes
as issued by the Quartermaster's Corps. These
should be kept fly tight and carefully fitted to
the soil surface. Daily policing and spraying of
the pits with crude oil should be practiced. Fly
traps set near the latrines aid in holding down
fly breeding and contamination.

Sewage disposal.--It is important to locate
permanent camps adjacent to towns or cities with
effective and adequate sewage disposal facilities.
In large camps the provision of sanitary sewers
with approved disposal plants is essential.

Sewage disposal systems must be watched
closely to prevent fly breeding. Sludge, especially
if not fully digested, is very favorable for fly
breeding. Heavy scum on septic tanks and sludge-
drying beds often produces great numbers of house-
flies. With proper operation of the disposal
plants, quick d3' i ng of the sludge, and the use

Circular 8 Flies

of borax when necessary, fly breeding in these
situations, however, can be largely prevented.

Protection of Commissaries, Kitchens, Mess Halls,
and Quarters from Flies

Screening.--All openings in building should
be protected with well-fitted screens. Windows
should have full-length screens and doors should
open outward. The screening should be at least
16 meshes to the inch so as to exclude mosquitoes
as well as flies. In moist climates non-corroding
metals such as cold drawn copper, bronze, or
monel metal are most serviceable. In dry climates
painted wire is satisfactory. Painting galvanized
wire when it is put up will prolong its life in
damp climates.

Fans and electrocutors.--Ceiling fans in-
stalled over entryways to mess halls and kitchens
aid in keeping flies out.

Electrocuting devices, if of proper construc-
tion and carrying 3,500 to 4,000 volts with low
amperage, are effective in killing flies that
strike them. They are used to some extent in
doors and windows and also as out-of-door trapping
devices. The initial cost of such equipment is
rather high and the odor of the burning flies
and the dead flies which occasionally fall on the
floor are objectionable features, especially in
mess halls and kitchens (see list of manufacturers,
Circular 20).

Fly traps.--The use of fly traps is an
important adjunct to ordinary procedure in the
prevention of fly breeding. Tremendous numbers
of houseflies and blowflies may be caught in prop-
erly constructed and properly baited traps set
in strategic locations.

Circular 8 Flies

Extensive experiments have shown the conical-
type trap, as shown in Fig. 6, to be the most
effective and easily handled. This type of trap
will catch on an average more than twice as many
flies as traps of the tent type. The traps should
be from 12 to 18 inches in diameter, with sides
and top built of screen and with a cone reaching
nearly to the top. The legs should be about 1
inch long. The frame of the trap may be made of
barrel hoops and laths or of galvanized iron.
The bait should be placed beneath the trap in a
broad, shallow pan about 4 inches less in diameter
than the base of the cone, and 1 inch deep. One
of these traps, properly baited, will capture about
as many flies as an electric grid of somewhat sim-
ilar size, and the cost of installation is much

Any substance attractive to the housefly
may be used as bait. Blackstrap molasses, 1 part,
and water, 3 parts, makes a convenient and attrac-
tive bait. Milk and fruit waste may also be

The traps should be set where flies natur-
ally congregate. This is usually on the sunny
side of a building (except in very hot weather)
and in places protected from the wind. Kitchens
and mess halls usually attract flies in consider-
able numbers and should have traps set near the
doors. The bait pans should be kept well filled
and should be washed out about every two weeks.
The catch is reduced when the flies become piled
more than a fourth of the way up the cone. At
such times the trap should be emptied. The live
flies in the trap at the time of emptying may be
killed by immersing the trap in hot water or by
the use of a fly spray The number of traps
required depends on the size of the area to be
protected and the abundance of flies.

Circular 8 Flies



I~z~ -

Figure 6 Conical flytrap, side view. A. hoops forming
frame at bottom; B. hoops forming frame at top; C. top
of trap made of barrel head; D. strips around door;
E. door frame; F. screen on door; G. buttons holding
door; H. screen on outside of trap; I. strips on side
of trap between hoops; J. tips of these strips project-
ing to form legs; K. cone; L. united edges of screen
forming cone; M. aperture at apex of cone.

Circular 8 Flies

Sprays.--Kerosene extract of pyrethrum is
effective Tin killing flies in tightly closed
rooms or tents if it is thoroughly applied as a
fine mist. The spray should contain the extract
of at least 1 pound of pyrethruin flowers with a
pyrethrin content of .9% in each gallon. Although
this material is not harmful to man, it is advis-
able to use it only when foods are put away or
well protected. An electric sprayer is most effec-
tive as an applicator, but large, well constructed
hand sprayers, if vigorously plied, will do the
work. See specifications on fly sprays (Circular
21) and discussion of spray equipment (Circular 20;.

Fly poisons, fly papers, and swatters.--
Occasional flies that gain entrance to mess halls,
barracks, etc. should be destroyed by using fly
poisons, sticky fly paper, and fly swatters.

The safest and most effective poison consists
of 3 teaspoonfuls of commercial formalin to 1 pint
of milk or water with a little brown sugar added.
A convenient way of exposing this is to fill,
partly, a drinking glass with the solution. A
small plate or saucer is then lined with a piece
of blotting paper and placed on the glass, bottom
up. The whole is then inverted, and a piece of
matchstick inserted under the edge of the glass.

Fly papers, either of the ribbon type or in
sheets, are useful in mess halls and kitchens.
A convenient way to use these is to tack them to
a board provided with a ledge along the bottom to
prevent drip, and suspend in out-of-way places
where the flies congregate.


Several species of the larger green and
bluish-colored flies with metallic sheen and gray
flesh flies visit foods and may inoculate them with

Circular 8 Flies

dangerous germs. The odor of cooking food, espec-
ially cabbage, turnips, and related vegetables,
is very attractive to these flies. They may
deposit eggs ("blow") on such materials, but are
more likely to infest meats, either raw or cooked.
Through the swallowing of the living eggs or lar-
vae of some of these flies severe irritation,
digestive disturbances, and pain sometimes result
(intestinal myiasis). Some of the larvae of these
flies also occasionally invade the genital organs
(urano-genital myiasis).

The adult of the true screwworm (Cochliomyia
americana C. & P.) is bluish green with dark
stripes on the thorax, Fig. 7. It closely resem-

Figure 7 Screwworm fly, female.

bles some of the other blowflies, but it breeds
only in living animal tissue. It is therefore
of primary importance because of its attack in

Circular 8 Flies

the larval form on domestic animals and occasion-
ally on man. Screwworas occur inainly in the South,
especially in Texas and Florida, and in Mexico,
the West Indies, and Central and South America.
Other blowflies occur in nearly all parts of the
world. A more detailed discussion of the screw-
worm is to be found in Circular 18.


Since World War I, methods have been devel-
oped for treating slow-healing wounds such as
chronic osteomyelitis, varicose and diabetic ulcers,
and burns with sterile blowfly larvae or certain
chemical compounds found in the excretions of these
larvae. The species most used for this purpose
are the common greenbottle fly, Lucilia sericata
Meig., and the black blowfly, Phormia regina 1eig,
This subject will not be discussed in this National
Defense series, but attention is directed to the
list of references at the end of this circular.


Blowflies breed mainly in carrion, although
some develop in feces, especially those of man and
hog, and in garbage, particularly if it contains
meat or meat wastes. The developmental periods in
different species of blowflies vary considerably,
and they are strongly influenced by temperature.
In general, these periods are similar to those of
the housefly.

The screwworm breeds only in living, warm-
blooded animals. It deposits its eggs on wounds,
and the larvae, which hatch in about 12 hours,
penetrate into the underlying and surrounding tis-
sues. This results in.swelling, inflammation, a
bloody discharge, and extensive erosion of these

Circular 8 Flies

tissues. In man the nose is frequently the site
of attack, although surgical or gunshot wounds,
or even minor scratches may become infested if
neglected. The larvae complete development in
4 to 10 days, and then drop to the ground to pu-
pate. The life cycle is complete in about 20
days. These flies may travel many miles from
where they emerge.


Refrigeration and screens play an important
part in protecting foods, especially meat, from

Disposal of Dead Animals

Prompt disposal of carcasses by burning
is the most important step in blowfly control.
This can be accomplished more easily where wood
is plentiful by using the trench method. This
consists of digging a trench aoout the size of
the body of the animal, filling this with wood,
turning the carcass over on the wood, and light-
ing a fire at the windward end, Fig. 8.

In cases where prompt burning or burial of
carcasses is impractical, the breeding of flies
in them and the odor emanating from them may be
prevented by spraying them with creosote oil hav-
ing a tar acid content of at least 10 percent.
Incinerators may be used if available.

Garbage Disposal

Garbage should be kept in fly-tight cans
and removed daily. Proper handling of garbage
at disposal plants and at hog-feeding farms is
important. These matters are discussed under
housefly control.

Circular 8 Flies


Conical fly traps, similar to those described
for use against houseflies, page 11, are useful
in supplementary control measures. The legs may
be blocked up so as to give about a 2-inch clear-
ance under the cone. Meat scraps, liver, or bet-
ter, "gut slime" (a packing house by-product of
sausage casing manufacture) kept moist with water,
are good baits.

Figure 8 Burning carcass by the trench method. The
carcass is consumed in a few hours by putting the
wood in a trench and turning the carcass over on it,
then starting the fire at the windward end.

Circular 8 Flies

Treatment of Screwworm Infestations

Screwworm infestation should be avoided
through personal hygiene and by sleeping during
the day only behind screens or under nets. Ani-
mal infestation can be avoided by preventing the
occurrence of wounds as far as possible, and when
they do occur, treating them every three days with
powdered diphenylamine. See also Circular 18.

In the case of human infestations, the
larvae may be removed with forceps after a judicious
application of chloroform applied with an atomizer.
Infested wounds in animals are treated by killing
the larvae with benzol (preverably applied as a
spray), carefully removing the larvae, and pack-
ing pulverized diphenylamine crystals into the
wound. If diphenylamine is not at hand dehydrated
acid-free pine tar oil with a specific gravity ot
1.065 should be applied each day to the wound to
repel the flies.


A number of different species of flies nor-
mally parasitic on domestic or wild animals occa-
sionally attack man. The most troublesome of these
is the human bot, Dermatobia hominus, Fig. 9, of
tropical America. The horse bots and cattle grubs
also attack man on occasion, sometimes producing
grave symptoms. Horse bot infestations in man
usually take the form of skin invasions dermall
myiasis). These are not difficult to deal with.
Further information on horse bots is contained
in Circular 16.

Circular 8 Flies


This parasite, known in tropical America
as "berne" or "torcel," is a common pest of cat-
tle, hogs, and various other domestic and wild
animals from central Mexico through Central Amer-
ica and over much of South America. It infests
the skin, forming swollen, discharging lesions.
The infestations of man occur mainly on the exposed

The pest
y ^ has not been thor-
oughly investigated
or methods of con-
trol worked out.
B-. ~It is known that
the fly at least
J . sometimes attaches
Sits eggs to the
bodies of other
insects such as
mosquitoes or
other flies, Fig.
10. When these
Figure 9 Human bot fly. latter insects
chance to alight
on a person or other warm-blooded animal the eggs
hatch and the bots, Fig. 11, penetrate the skin.

Prevention and Treatment

No control procedure has been developed.
Infestations may be held down by keeping the per-
son protected as much as possible from the attack
of biting insects.

When infestations occur, the larvae may be
squeezed out or killed by applying benzol or chloro-
form to the openings through the skin, after which
the larvae should be removed and an antiseptic
applied to the point of attack.

Circular 8 Flies

Figure 10 Eggs of human bot fly attached
to the abdomen of another fly.


Eye gnats (Hippelates) are very small
(about 1/16 inch long) black or yellowish flies
that have a strong tendency to hover around the
face and eyes of people and also to visit food
to some extent. They are strongly attracted to
wounds and discharges from natural body openings.
They also feed upon garbage and excreta, and
hence are capable of taking up and transferring


Circular 8 Flies

many kinds of germs. There is abundant evidence
that they are responsible for much eye infection
and may transmit the serious tropical disease of
man called yaws.

Figure 11 -
Larva of
human bot
fly (after

Eye gnats are most abundant
in the southern portions of the
country, and in the irrigated areas
in the Southwest they may occur
in alarming numbers.

These gnats are so small
that they can pass through ordi-
nary screens with ease. They
prefer bright light; therefore,
are not very troublesome in build-
ings except in rooms with many
windows or on porches.


Eye gnats breed mainly in
cultivated soil containing decay-
ing vegetation and manure. They
prefer the lighter types of soils
and those with considerable mois-
ture. They may breed to some
extent in garbage and are attracted
to places protected from strong
winds and to the shade in hot


Little can be done by military units to
prevent breeding. Reducing the cultivation of the
soil to a minimum around camps should reduce breed-

Circular 8 Flies

ing in the immediate area. The eggs are laid
on the soil very soon after it is broken by plow-
ing or cultivation. Breaking, harrowing, and
rolling the soil in one operation appears to
reduce breeding. Keeping attractive materials,
such as manure and garbage, covered and removing
them frequently is an aid in control.

Traps of a special
around the camp in places

design, Fig. 12, placed
where gnats occur in

Figure 12 An improvised eye gnat trap. The liver and
water bait is placed in the bottom of the can, and the
gnats, after feeding, enter the jar and die.

greatest numbers will reduce gnat abundance to
a large extent. Systematic operation of traps
around schools has been shown to aid materially
in the reduction of the incidence of purulent

Circular 8 Flies

Fly sprays (pyrethrum in oil) kill the
gnats actually struck and repel others for a
short time. Pyrethrum concentrate (1-20*) and
lubricating oil (No. 10), 20 parts, lightly painted
on window screens will keep gnats out for several
hours. This is particularly useful in infirmaries.

A light application of fly spray to the face
and garments will repel the gnats for a short


There are many different kinds of blood-
sucking flies. Some of these are of considerable
importance as annoyers of man and livestock, and
they are of some importance as transmitters of
disease. Their role in the transmission of dis-
ease in the Americas is mainly of a mechanical or
accidental nature. Anthrax and tularemia, or
rabbit fever, are the maladies with which they are
most frequently associated. These diseases are
transmitted to both animals and man by horse
flies and deer flies (family Tabanidae). It is
probable that stable flies, Stomoxys calcitrans,
Fabr., also occasionally transmit these maladies.
These flies are often extremely annoying by their
painful bites (see Circular 17). Buffalo gnats,
or black flies, (Simuliidae) are abundant and
annoying locally. They are not known to trans-
mit any disease in the United States; however,
in parts of Mexico and Central America certain
species transmit the worm Onchocerca which causes
a serious disease of man often resulting in blind-

*Extract of 20 lbs. pyrethrum in 1 gallon
of kerosene.

Circular 8 Fliesa

ness. Sand flies (Culicoides) are extremely
troublesome to man and livestock in certain regions.
The flies referred to above have very dif-
ferent breeding habits, and the control procedure
must vary accordingly. Where trouble is exper-
ienced, specimens of the fly causing the difficulty
should accompany requests for further information.


Horse flies, Fig. 13, and deer flies, Fig.
14, breed in marshes or swamps, along streams
with marshy banks,
and in meadows over
which irrigation
Y4 water is allowed to
run continuously.
Location of camps
on well-drained
/sites away from
marshes, improved
drainage and clear-
ing, and the use
of screens are the
methods of control
or protection which
have to be relied
upon. Repellents
are practically
valueless against
horse flies.

1 .,Figure 13,- A horse
fly, Tabanus atratus F.

Circular 8 Flies

/ '\

Figure 14 A deer fly, Chrysops nigra Macq.


Buffalo gnats, or black flies, Fig. 15,
are small heavy-bodied flies that breed in run-
ning water. The larvae attach to sticks, stones,
and other objects in the swiftest portions of
streams, and the gnats often emerge in swarms.
There is usually a single brood each year, and
fortunately the season of activity is rather short.

Control measures have not been well worked
out. Removal of stones and brush from streams
reduces the opportunity for breeding. The treat-
ment of small streams near camps with pyrethrum
larvicide (see Circular 21) will destroy the larvae.
Nets or screens should be placed across the stream
to prevent fish that may be stunned by the insec-
ticide from floating downstream with the material.
The dosage required under different stream condi-

Circular 8 Flies

tions has not been determined. Smudges give
both man and livestock some protection, and pyre-
thrum concentrates, mixed with No. 10 lubrication
oil 1 to 5, mopped or sprayed on, give some relief.

Figure 15 Adult black fly.


Minute biting midges, Fig. 16, known as
sand flies, punkies, or no-see-urns, are trouble-
some pests of man and livestock in many parts
of the country. There are many different species,
and these show destructive breeding habits.

Circular 8 Flies

All breed
* in water or very
\ damp places. The
Larvae, Fig. 17,
SIof certain species
Share to be found
Sg among leaves and
L other decaying vege-
Stat ion or in manure
along the margin
of streams. Others
Q breed in rot holes
in trees that are
Si, capable of holding

Figure 16- Adult sand

most serious
annoyance from
these pests
occurs along
the Atlantic
and Gulf Coasts
and in the West
Indies and Cen-
tral American
countries. These

Figure 17 Larva
of sand fly.

Circular 8 Flies

pests breed in open, grassy salt marshes where
the tide is not too active, also in mangrove and
pickleweed marshes along the coast of Florida
and countries to the south. Breeding is more
profuse in areas where fresh water enters the


The eggs, Fig. 18, are laid on the mud
near the water. They hatch in a few days, and
the slender larvae can either burrow in the thin
mud or swim about in the water. The larval stage
varies from a few months to 6 or 8 months. Pupa-
tion, Fig. 19, takes place in the mud. Sand flies
apparently do not spread more than 2 or 3 miles
from their point of emergence.

Figure 18 Eggs of sand Figure 19 Pupa of sand fly.


Sand fly larvae are susceptible to drying;
therefore, removal of water from a breeding area
is the most satisfactory control. Unlike mosqui-
toes, they can live in mud, so more complete dry-
ing is necessary than is required in mosquito

Circular 8 Flies 30

It has been found possible to largely elim-
inate the pest by construction of dikes around
prolific breeding areas and removing the water
from behind the dikes by tide gates or pumping,
or both. In order to concentrate the water and
more completely dry the diked area, a ditching
system is usually necessary. Since some sand
flies develop in the mud along the ditches, the
number of ditches should be reduced to a minimum,
and these should lead directly into the large band
ditch running along the dike.

Woods adjacent to camps should be inspected,
and rot holes found should be cut out so they
will drain, or they may be sprayed or painted lib-
erally with creosote oil.

Sand flies can pass readily through ordi-
nary screens, and thus they often become very
annoying in well-screened buildings. This can
be prevented by painting the screens lightly each
evening with 1 part of pyrethrum concentrate (20
to 1) in 20 parts of light lubricating oil (S.A.E.5).

This repellent mixture may be applied to
exposed parts of the body to protect against sand
fly attack. Oil of spearmint or oil of sassafras
is also of some value as a repellent.

The location of camps on areas well removed
from sand fly breeding places is advised, and plac-
ing the camps in exposed places is helpful since
sand flies are not troublesome in a strong breeze.
Sand flies are attracted to light to some extent;
therefore, on still nights when these gnats are
bad, illumination of quarters should be avoided
as much as possible.

Circular 8 Flies


Stable flies, dog flies, or biting house-
flies (Stomoxys calcitrans Fabr.), Fig. 20, as
they are variously known, are grayish flies resem-
bling the common housefly, but slightly more robust
and with a strong blood-sucking beak. They breed
in manure and many kinds of fermnenting vegetation.
They are produced in tremendous numbers in straw
mixed with urine and manure of horses, cattle, or
hogs, in straw stacks that have become wet by
heavy rains soon after thrashing, in seaweed washed
up on beaches under certain conditions, and in
large accumulations of weeds, hay, manure, and
other debris left in fields or deposited by floods.


Figure 20 The stable fly,
Stomoxys calcitrans.

Caring for man-
ure and other vegetable
refuse as recommended
for the housefly will
largely prevent stable
fly development in
such material. These
flies travel consid-
erable distances, and
the cooperation of
farmers and others
in the vicinity of the
area to be protected
is therefore necessary
for best results.
This fly is not cap-
tured in any numbers
in traps designed to
catch houseflies and
blowflies; however,
electric grids, if

Circular ? Fies

properly placed, especially in windows of stables
containing 'ivestoci, will destroy large numbers
of them. Repellents are of little value, cut
these flies are very susce-tible to pyretharum-
oil says if `te can be struck by the spray.
Further det ais on control are aver. in Circular

__ J7C S


i o 1916,
tion. E D e rt r
::o. 733. 14 3P.

and their



7. 1937. he control of flies on
d ra cattle an around dairy buildings.
". 3 n At r., t r- o.' tooiolPy
and_ ?ant ;uare~ntine. E-267. 3 PP.


0 C.
S-. ne

1937. F
Bur. of
,. E-305.

ly s2rays.
2 pp.

3, Dept
Plant -uar-



a e a-" Pp-a -rL- D,
F. C., Laake, .,., and Paran, D. C.
1S26. 3cre'..vor's and other maggots affect-
in- ani-als, U, 3. ept, t r. -arers'
Bu'lletin ::o. 57. 13 pp.

. 1935. The eye at in the Coachella
Valley, California. . Dept. Agr.,
E'ur. of .-tocloy and Plant -uarantine.
- '5 7 : .

raha=-S=ith, 3. 1916. bservations on the
habits ,nd p arasites of cc-_on flies.
.ara3::lc-.,, 7. -, no. 4, 440-544.

Circular 8 Flies 33

Graham-Smith, G. S. 1919. Further observations
on the habits and parasites of common
flies. Parasitology, v. 11, no. 3-4,
Pp. 347-384.

Hewitt, C. Gordon. 1914. The house fly, tiusca
domestic Linn., its structure, habits,
development, relation to disease, and
control. Cambridge University Press.
382 pp.
Howard, L. 0. 1911. The house fly disease car-
rier. Stokes & Co., N. Y., 331 pp.

Howard, L. 0. and Bishopp, F. C. 1925. The house
fly and how to suppress it. U. S. Dept.
Agr., Farmers' Bulletin No. 1408. 16 pp.

Parman, D. C. and Burgess, R. W. 1931. Some of
the more significant results of recent
work on eye gnats (Hippelates) and sug-
gestions on control of these gnats and
of flies in Coachella Valley, California.
U. S. Dept. Agr., Bur. of Entomology.
E-288. 3 pp.




W'm. 1933. The culture of sterile mag-
gots for use in the treatment of osteo-
myelitis and other suppurative infections.
U. S. Dept. Agr., Bur. of Entomology.
E-311. 10 pp.
Wm. 1933. Problems in the application
of the maggot treatment of osteomyelitis
and other suppurative infections. U. S.
Dept. Agr., Bur. of Entomology. E-312.
7 pp.
Wm. 1937. The healing properties of
allantoin and urea discovered through the
use of maggots in human wounds. Smith-
sonian Institution Report for 1937, pp.

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