The Insect pest survey bulletin

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Material Information

Title:
The Insect pest survey bulletin
Physical Description:
v. : maps ; 26 cm.
Language:
English
Creator:
United States -- Bureau of Entomology
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
Bureau of Entomology, U.S. Dept. of Agriculture
Place of Publication:
Washington, D.C.
Publication Date:
Frequency:
monthly, mar-nov. plus annual[1926-]
monthly, apr.-nov.[ former 1922-1925]
monthly, may-nov.[ former 1921]

Subjects

Subjects / Keywords:
Insect pests -- Periodicals   ( lcsh )
Entomology -- Periodicals   ( lcsh )
Genre:
serial   ( sobekcm )
federal government publication   ( marcgt )

Notes

Dates or Sequential Designation:
Vol. 1, no. 1 (May 1, 1921)-
Numbering Peculiarities:
Vol. 14, no.9 issued only as a supplement..
Issuing Body:
Vols. for May 1, 1921-1934, issued by the U.S. Bureau of Entomology; 1935- by the U.S. Bureau of Entomology and Plant Quarantine.
General Note:
"A monthly review of entomological conditions throughout the United States" (varies slightly).
General Note:
Includes annual summary starting in 1926.
General Note:
Includes some supplements.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030368280
oclc - 08816534
lccn - sn 86033699
Classification:
lcc - QL1 .I56
System ID:
AA00023228:00138

Full Text








THE INSECT PEST SURVEY


BULLETIN


Volume 18 Supplement to Number 1 March 25, 1938


BUREAU OF

ENTOMOLOGY AND PLANT QUARANTINE

UNITED STATES

DEPARTMENT OF AGRICULTURE

AND

THE STATE ENTOMOLOGICAL

AGENCIES COOPERATING


LIBRARY
STATF. PLANT BOARD













I NI SE C T


PEST SURVEY


Vol. i1 Supplement to Num-ter 1 March 25, 1935



SAL_7AL IL SURVEY, FALL OF 1937

W. C. _IcDiff ie. F. V. Lieterman, and R. ".;. T21
Ags;t-'nt Entomologist.
Division of Cereala,-nd FgIorae Insect Investintions-'
'u'ren. o E_.-it ,-jo lovy a'rid Pla:nt 'rr:i.t i ne
'. S. l.' D-rtn1t of Aoric'.lture



F-OSE OF SURVEY

A'nui.l surveys of alfalfa weevil:-abundance in the fall of the
year were begun in 1932 in order to indicate the outlook for weevil
damn:-e in the following year and to create a reliable record of re,-im-
al abundance which mi-ht later be useful for studying the effects of
climate upon the weevil. The surveys also reveal the gross n-'r-' ncq
of cocoons of the larval p-rcnsite Bathplectes' curculionis (Torns. ) /
and, by dissection, the number of these that are vin'ble. As the sur-
vey results are of ij :'.liite practical value to entomologists and
county agents in a large part of the weevil-infested region, the poli-
cy of publishing them was begun with the results of the 1936 surve-y.-




-/The work on which this report is based was carried out under
the direction of J. C. Hiamlin. The survey in Jackson Couity, Oreg.
was planned and executed by R. C. :Te-ton. General assistance was pro-
vided by L. J. Jones and J. B. Dunccan.

2/Hypera postica (G yli.)
3/All later mention of parasites in this p-per hri reference to
this species.
-!LIcDuffie, W. C. Alfalfa Weevil Survey, Fall of 1936. U. S.
Dept. Agr., Bur. Ent. and Plant quar., Insect Pest Surv. 3ul. 17:
29-42, March 15, 1937.


-33-


BULLET IN









-34-


EXTENT OF SURVEY

As in 1936, the districts surveyed were restricted to those
considered most important in regard to alfalfa culture and weevil
damage. Twelve districts were sampled, and these included portions
of Oregon, Idaho, Utah, Colorado, Nevada, mnd Nebraska.

METHODS

The sampling plan was the same as that followed in 1936, 4
representative square-foot samples being taken from each of 25 fields
in a district, except in the smaller districts, where 12 fields were
considered sufficient. Such sampling does not give highly accurate
estimates for individual fields but provides a useful indication of
the general level of weevil abundance in a district.

Each sample was taken by forcing into the soil a metal die 1
foot square and removing all alfalfa crowns, litter, and weeds en-
closed by the die, as well as the soil from the enclosed area to a
depth of from 1 to 2 inches. Later, each sample was reduced in volume
by washing, so that its content of weevils, parasite cocoons, and
litter remained in the lower of two screen-bottom tubs. These washed
samples were individually wrapped in absorbent-paper towels to remove
excess moisture and were examined in the laboratory on a white porce-
lain tray.

LIMITATIONS ON USE OF DATA

Obviously no forecast of weevil damage (or parasite effective-
ness) can be exact. Nevertheless it is believed that considerable loss
can be averted if interested State entomological workers and county
agricultural agents will watch developments in those localities in which
the survey has indicated a prospect of important damage by the alfalfa
weevil. Our interpretation of survey data is based on the generality
that an average population of two adult weevils per square foot is neces-
sary to produce economic damage in most of the older weevil-infested
territory. However, the outlook'gained from surveys made in the fall is
subject to modification by mortality of adult weevils during the winter,
Also, the amount of damage in any locality depends on whether spring
weather favors or hinders weevil development. Again, certain field con-
ditions manifested by thin stands or poor growth may aggravate the
damage in any field or in any district where these conditions prevail,
because fewer adult weevils are required to create a larval concentration
sufficient to cause.dnmage. Finally, injury in any field populated by a
menacing number of larvae is increased by delay in harvesting after the
plants are mature. Such maturity is indicated by budding Of the top crop,
together with scattered blossoms and appearance of the earliest basal
shoots of the succeeding crop.










-35-


RE 0TA S

Results of the 1937 fall survey are grouped by States and tabiu-
lated by districts, each tabulation being -iccrip-nied by a brief dis-
cussion. All averages in the succeeding tabulations have reference to
areas of 1 square foot. It has also been considered helpful to include
a brief summary of the extent of weevil dr.inge which occurred in each
State during the :rowin. season of 1937.

ORE GON

First-crop damage by the alfalfa weevil in 1937 amounted to 10
and 35 percent, respectively, of fields in Jackson:i County and in Eagle
Valley, Baker County. Economic loss, however, was slight in both areas,
larval feeding being largely restricted to the tips of alfalfa plants.
In Engle Valley (table l) one-sixth of the alfalfa fields surveyed were
populated by a menacing number of weevils. Additional injury may de-
velop in'hillside fields occupied by smaller weevil populations, because
of poor growth and thin stands, as was the case in 1937.

Ordinarily the parasite population would be effective in minimiz-
ing production of the new-generation adult weevils, which will form the
basis of attack in 1939, but the late-cutting practice prevalent in this
area largely nullifies the beneficial effects of parasitization.

Table l.--Survey results Eagle Valley, Baker Comunty. Oreg..
*sampled September 29. 1937


Field No.


H. postica
adults
ITxhbe er


B. curculionis cocoons
Present : Viable
T' ,ber T:.,.er


1 -- -
41
2
3
4 - -
5


9 - -
7--



10 - -
11 - -
12 - -


e r5.46 1 l.l1


1.00
.75
1.25
1.00
2.25
1.25
.75
1.75
2.75
0
1.75
0


3.50
11.25
7.00
7.00
2.25
1.25
3.75
2.25
13.
8.75
2.75
2.75


1.00
.75
1.50
.75
.25
. 50
1.75
.75
4.25
1.75
. 50
.50


-Average -


1.21









-36-

Malheur County was oaitted from the 1937 fall survey, two
seasons' study having shown no appreciable differences between alfal-
fa weevil conditions in this county and in Canyon County, Idaho. The
latter county is typical of the lower Snake River Valley of western
Idaho and eastern Oregon, and survey results for it serve as an indi-
cation for adjoining counties in Idaho and Oregon.

In Jackson County (table 2) approximately 50 percent of the
fields surveyed were inhabited by threatening weevil populations. The
parasite, first introduced into this area in 1934, was recovered from
every field examined in the fall of 1937. Its increasing abundance
indicates that it :iay develop into an important factor in alfalfa weevil
control for this area. .

Table 2.--Survey results. Jackson County. Ore..
sanpled October j-28., 1937


Field No.


5.----- -.--

. ... . 5 ...
77

5
7 - - - -

10 - - -
11 - -- - -
12 -- - ---
13-- -----
114.--------
15- - -- -
16-------
17-------

19---- -7 ---
20 - - - -
21. - - -
22- - - -
23 - - - -
214.------- --
25- -----

SAverage-


H. postica
S adults
ITu-ib,-r

S2,50
* 3.50
1.00
1.50
1.00
0
1.25
.25
.75.
1.25
.25
1.50
.25
2.50
2.50
2.00
3.00
S 1.75
2.25
4.50o
3.25
2.25
4.00o
4.25
1.75

1.96 -


B. curculionis cocoons
SPros;Ent : Viable
: ztu-bur : N'u-b,.r

4,25 .' .50
: 2.00o .75
S 9.7.5 3.?5
'6.o00 .75
.50Q. 1.50
2.50 1.00
6.50 : 1.75
4.50 : 2.75
3.00 : 1.75
.25 .25
2.25 .50
6.50 : 2.50
6.00 1.50
4h.25 : 2.00
3.75 1.50
7.25 : 3.75
5.25 : 2.50
1.75 : 0
g.oo : 2.25
.25 1.25
.50 : 1.00
5.25 .75
S 2.75 : 2.00
50 .25
2.50 : 1.50
S .i*
4.36 1.5S
*










-37-


Alfalfa weevil &'v-gc in the lower Snake River Valley of western
Idaho was negligible in 1937, affecting only about 2 percent of the
fields. The injury was largely concentrated in Ada County. Approxi-
mately 10 percent of fields in eastern Idaho (upper Snake River Valley)
were injured, but only in "in-Tham County was the d-:'.-.;e severe.

The survey in eastern Idaho again included parts of five counties,
viz, Bin.hai, Bonneville, Jefferson, :,adison, and Fremnont. The first
two counties were treated as a subdistri.ct, because a somewhat longer
growing season occasionally permits harvest of three alfalfa crops. eb'
other three counties are strictly two-crop areas and were treated as a
separate subdistrict. In Fonneville and Bingham Counties (table 3) po-
tentially injurious weevil populations existed in approximately one-
fourth of the fields examined. Fall abundance of viable parasite cocoons
promised highly effective parasitization for 1938.

Table' 3.--Survey results. Bingham, and lonneville Counties,
Idaho, sampled September 13-14, 1937


Field No.


1 -
2

4-
5-
6-
7-
8 -
9
10 -
11 -
12 -
13 -


H.. postica
adults
!u-b e r


1.00
.75
1.75
1.00
2. O0
2.50
2.50
1.00
.25
.75
1.00
1.25
.75
3.00


. B. curculionis cocoons
SPresent : Viable
I iTu- 'c-: r : Tumber


4.50
17.75
21.75
4.50
10.25
5.25
2.00
3.50
1.00
19. 50
16.50
12.00
3.75


3.25
4.75
3.75
.50
2.00
2.75
1.00
0
.50
4.50
2.00
2.25
.50


Average -


1.35


9.4o : 2.13


In Jefferson, Madison, and Fremont Counties (table 4) one-third
of the fields surveyed were populated by a menacing number of weevils,
and considerable da--. -.-e for 193$ was indicated. Viable parasite cocoons
were sufficient to minimize production of new-g.eneration weevils in 1938.



I BR ARY
rI1,., L\T BOARD












-39-


Table 4.--Survey results, Jefferson. Madison, and Fremont Counties.
Idaho. sampled September 14-15. 1937


Fl N a
Field No. : I a


: M

*
*
' -
*
*
*
*
*
*
*
*
*
*
*
*

*
* .
*
*
*
* __________ __


Average -


ostica
dults :
iuzmber

.50
3.25
3.25
1.25
1.25
.75
1.00
.75
5.50
1.25
2.75
1.25

1.90


B. curculionis cocoons
Present : Viable


Number

9.00
30.00
3o.oo

9.25
4.50
6.50
17.25
14.75
15.75
5.75
10.75.
24.25
2.25


11.67


NTub e r

1.75
3.50
1.75
50
50,
5.75
.75
.75
.50
.75
1.00
1.00


1.54


The survey of western Idaho was limited in 1937


to Canyon County,


it being considered typical of the important alfalfa-growing area of
western Idaho and eastern. Oregon.

In Cahvon County (table 5) only slight weevil da-iace is expected
in 1935. Of- 5 fields, 2: were populated by threatening numbers of
weevils. No6 adult weevils were found in about half the fields examined.
Parasite cocoons were scarce but were cormensurate with the small weevil
populations.









-39-


Table 5. -Surve results Canyon Coty _
Se-tcnber 30-October 1. 1937


Field 1To. H. postica B. curculionis cocoons
a adults P Pres int : Vible1
I umbePr Y uiber r.1^. 3r
1 - - - 0 1.25 .50
2 - - - 0 .25 .25
3 : 0 0 --
4 - - - 0 1.25 .50
5- - - 0 0
6 - - .50 13.50 : 1.25
7 -0 2. CO 1.00
g 1.0- : 1.50 .25
9 - - - .25 1.50 .25
10 0 1.0 : 0
11- - - 1.25 17.00 : 1.25
12 1.00 1.25 .50
13 - - - .25 5.50 0
14 - - - 1.25 1.50 .25
15 - - - 0 1.75 -25
16 -0 .75 : 0
17 - - - .50 .50 0
1 - - - 0 2.00 .25
19 1.00 1.25 .25
20 - - - 3.00 7.75 1.25
21 -- - - 2.50 10.00 .75
22 - - - 1.00 1.75 : 0
23 - - - .50 1.25 .25
24 - - -: 0 1.25 25
25 - - - 0 2.00 .25

Averge 0.56 3.14 : 0.38



Weevil damage in 1957 occurred in 5 percent of th- alfalfa
fields in Box Elder, Srlt Lake, and Sn.pete Cointies and amounted to
less than 1 percent in Sevier County. 'he most g-oneral injury oc-
curred in Millard County, where 50 percent of the first crop was
severely drni.-ed. In Box Elder County (table 6) serious d-c'.--.e is
indicated for 1938, as threatenin.- weevil populations existed in 4o
percent of the fields during the autumn. Abzdance of parasites
promised usual effectiveness in mini'mizing production of ne'T-,r. ra-
tion weevils from larvae on the first crop in 1935.










-4o-


Table 6.-Survey results, Box Elder County, VUtah. sampled
October 20-21, 1937-,



Fold :H. postica :B. curculionis cocoons
Adults Prtsent : Viable


Number


1 .- -
2--
3 - -
3

5
6--
7
9--
10 - -
11 - -
'12
'12 - -


15 --
16 - -
17 - -
18 - -
19 - -
20 - -
21 -- -
22 -
23 -
24 -
25---


.25
S 1.00
1.00
2.50
.75
: 3.00
:, 2.50
S 2.25
1.25
2.50
0
S 1.00
1.25
6.50
.50
.75
2.50
0
1.25
.75
2.25
3.oo
S .25
1.50
3.00

1.66


Nwiib 3r

1.00
. 50
5.oo
3.00
1.75
2.25
S.00
16.50
5.25
16.75
6.25
3.75
.25
7.50
7.25
l4.00
5.25
.50
0
-*50
3.75
2. 50
9.25
4.75
3.25
14.75


: T~lu^ber

1.00
0
1.75
S .75
1.00
2.25
3.00
1.50
2.25
4.00
1.50
0
1.75
: .00
06.0
4.00
1.00

.50
2.25
.25
.50
2.50
: 1.25
3.50


Average -


5.98


1.82











-41-


In Salt Lake County (table 7) one-sixth of tho fields surveyed
were inhabited by potentially injurious numbers of weevils. Viable
parasite cocoons were very abundant and indicated highly effective
parasitization in 193g.

Table 7.--Survey_ results. Salt Lake CountZ, t-ahs.-ipled
October 8-13., 1937


Field No.


1 -
2 -


5
6--
7-

9-
10 -
11 -
12 -



2o
15 -
16 -
17 -
18 -
15 -

21 -
22 -

25 -
25 -


SH. postica
: adults
S "" 'LL :'oer


50
1.00
.50
.25
.75
4.00
.75
2.25
1.25
.50
1. 00
.75
1.75
.75
50
0-
... o
1.75
2.00
1.25
6.25
.25
.25
1.00
.50
.25


B. curculionis cocoons


Present


LL 'imber

1.50
19.50 .
* 6.25 :
13. -00
9.00
13.50
16.50
21.00
24.75
11.25
3S.25
12.25
11.75
22.00
32.50
2.00,
6.25
5.75
9.75
12.75
5.25
39. co :
5.50
10.00


r 1.20 13.97 : 2.32


: Viable


U~lub e r
1Tiunbe-,r

1.00
2.91
2.50
.50
2.75
1.75
4.75
4.91
2.15
1.50
.31
5.50
1.00
4.32
2.17
.50
.75
1.75
.25
2.25
1.75

10.74
1.25
.75


Average -












In S:inppte Comunty (table 8) threatening weevil populations
existed during the fal.l in approximately one-third of the surveyed
fields. The survey indicate'& inadequate parasitization for 193S.

Table 8.--Survey results, Senpete County., Utnh, sampled
iovenber 19-23, 133


Field HTo. : H. postica : B. curculicnis cocoons
adult s : Present : Viable
: NTumber IN u. ber : IT'.b L r
1 3.00 16.75 1.25
2 - - - 1.75 9.O0 : 1.25
S.25 : .75 .50
2.25 .4.75 -.50
5 - - - 2.00 6.50 5o
6 : .75 3.50 .25
.7 50 11.67 : 2.00
: 75 :1.o 50
9 --- 5- -.50 : 01.00
10 - - - -0 o 7.50 .75
S11 - - 2.25 13.-00 ,33
12 - - - 1.50 -4.75 : 1.00
13 --- : 1.25 : 7.25 .50

Average : 1.63 7.46 0.g6
*


-42-
















In Sevier County (trible 9) fall -tbundance of weevils in sur-
veyed fields indicated damage to approximately S percent of the al-
falfa crop for 1938. Living parasites existed in smrll numbers but
were coruiensurate with the low level of weevil abundance.

Table 9.--Survey results. Sevier CountY. Utah. sampled
vownber 22-23. 1937


Field No,


H. postica
adults


: B. curculionis


-re ent


1 - 1
2 - -
3,



5--

51 - -
7'
9
I0 - -
8I --i


4.*29 0.55


cocoons


ViaDle


I~u.'-ib'ar
Ilutmbe r

.50
1. 50
1.75
2,.00
1.25
-.50
i1.00
.50
25
0
0
0

0.77


3.00
9.00oo
.25
2.25
.9.50
4.75
:2.25
7.50
.1.25
:9.00
.2.25
:0


ITumb e r

1.00
1.50
0
0
.50
.75
.75
.50
50
.50
.75


Ave ra











COLORADO

Of the first alfalfa crop in Mesa, Delta, and Montrose Counties,
5, 25, and 5 percent, respectively, experienced slight economic damage
from the alfalfa weevil in 1937. Damage was expected in 75 percent of
the Mesa County fields but failed to materialize because of drastic
winter kill of adult weevils present in the fall of 1936. In Delta
County (table 10) a_-proxi:iately one-fourth of the surveyed fields were
occupied by threatening weevil populations. Parasites promised to be
effective in curtailing production of weevil adults from first-crop
larvae. '

Table 10.--Survey results. Delta County. Colo., sampled
November 22-30. 1937 ....


Field ITo.


H-. pnstica
adults


2.50
.50
1.25
.75
2.50
1.25
..75
1.50
.75
1.50
3.00
.25
.25
.25
50
S50
0
c~o
1.75
2.50
S50


B. curculioris cocoons
SPresent : Viable


:Tuuber

5.,75
75
.75
7.75
-775
01
1.75
6.75
S50
10.75
1.25
0
50
3.75
14.25
3.25
.25
11.75
9.25
9.50
2.00


!urib e r

2.00
.75
0
5.75
.25

1.00
1.25
.25
1.25
1.00

0
.25
.75
.75
.25
5.00
3.25
4.25
.50


1.46 : 4.35


1.26


Average-....:















In Montrose County (table 11ii) approximately 10 percent of the
fields surveyed were populated by potentially injurious numbers of
weevils. Viable parasite cocoons occurred in small numbers but were
in keeping with thel weevil abundance.


Table ll.--Survey


results. Montrose County, Colo., saqjled
November 22. 1937


Field No.


Average- - -


H. postica
adults
i'umb er
.25
25
1.25
2.25
.25
0
l.OC
1.25
C


0.72


B. curculionis cocoons
P Present : Viabe1e
S Tub er : -.-'.u r
S50 .25
*5.00 0
6.O0 : 2.50
S 6.25 : 1.00
S 3. 50 50
2.75 .25
* 2.75 : 0
2.50 : 1.50
0 --


3.03


0.67


In Mesa County (table 12) the. survey indicated rather general
weevil danago for 193S, as 214 percent of surveyed fields were in-
habited by a menacing, number of weevils. Injury to fields populated
by smaller numbors of weevils may also develop because of generally
poor growth of the first 'alfalfa crop in this area, and dn-,na.-, nay
affect as much as 40 percent of the crop. Fall abundance of viable
parasite cocoons promised effective parasitization for 1938.


1 -
2


5
6-
7

9-












Table 12.--Survey results, Mesa County., olo., sampled
06tober 4-Novenmber.12. 1937


1 -
2
3
4
5-
6-
7
85-
9-
10 -
11 -
12 -
13-
14 -
15 -

17

19 -
20 -
21 -
22 -
23 -
24 -
25 -


H. sca B. curculiOniS cocoons.
: ; r:snont : Viable


Field No.


*



*










-- F
- -. -, -, e S. -








11
*- ** ^ -
*


T* Tmbeer

6.50
3.75
3.50
3.75
6.oo
4.:oo
2.50
15.75
6.50'
13.25
8.50
4.oo
1.75
7.75
14.75
3 .00
10.25
..... 2.1 5-
2.00
0
2.75
6.25
15.00
.75
5.25


2T:umber

1.75
S3.50
1.25
.25
1.25
S1. 00
.25
1.75
.25
2.00
S .50
: 0
S .75
.25
S1.00
.25
S3.50
P4,
S1.00

S1.50
1.25
S1.75
0 0
2.00


Average - -: 1.l4 : 6.15 : 1.09


NEVADA


Losses front the alfalfa weevil in western Nevoda during 1937
were slight except in Douglas County, where 50 percent of the fields
were severely drn-vi'-ed because very l1,.rre acreages 1revent"d tinely
cutting. Washoe County experienced fror: slight ,r(on.r, ic d&1iFge to 10
percent of the first crop. In Churchill County less than 1 percent
was injured.


IT .xnbe r

.75
2.25
.25

1.50
2.25 :
1.50
.25
.1.25 :
2.50
.25
.25
.75 "
50
J1.25 :

l. O :
50 .....
1.50
1.00
I-. O :

2.00
.50
0















-47-

In Dou-las County (tnble 13) one-sixth of the surveyed fields
were inhabited bb threagtenir- numbers of weevils, aIs was the case in
the 1936 survey. Because of the widespre-i.iL d- nna-e in 1937, develop-
ments, especially on large alfalfa. acre',-es, should be watched closely
with a view to possible insecticidal treatment, as this is the aost
satisfactory means of control for this area. Living parasites were
abundant and ordinarily would be highly effective were it not for the
late cutting practiced in this district.

Table 13. --Su-rvey resu.ilts. Dlo -la .3 County.v. .i
S* ovebler5..3


Field ITo.


1 ------ ----
2 -- -----
--

5--------
7--------






12------

5vera o- -


H. Los ica
adulb es
'"^*rb e r


- S
- S



- S


.50
.25
1.25
3.00
4.75
!. 5n'
1.25
.25

1. 25
1.25


3. curculionis cocoons
Present : Viable
ITumb er : 'rimber

6.00 : 1.75


1.25
1l/.25
.21.25
29. O0
.59.5o
7.50
9.75
19.oo
1V.25
S. 50
2...25


S50

2.30
5.53
2.3a
2. 04

1.75
1.75
.75
0
1. 43


1.33 15.63 1.79


15.-03


".3


1.79











In Washoe County (table 14) menacing weevil populations existed
in one-third of the fields surveyed. Parasite cocoons were abundant
but their viability was very low and indicated ineffective parasitiza-
tion for 1938.

Table 14.--Survey.results. Washoe County. Nevada. sampled


November


7-8. 1937


Field No.* H. postica .3 curculionis cocoons
:iel adults : Present : Viable
Number : Number : Number

1 - 2.25 19.50 1.33
2 - - - - 53.25 3.25 1-50
3 - - - - -: 1.25 4.25 .75
4 - - - - .o .75 -50
5 - - - - -.50 8.25 .25
6 - - - - - 2.00 : 17.25 1.25
7 -------- 1.25 3.25 0o
g .75 2.50 0o
9 - - - - .75 :.75 0
10 - - - - -.25 13.50 1.25
11 -------1.00 8.25 2.00
12 -------9.50 68.75 .50

SAverage - - 1.9S 13.19 0.77











In Churchili Oounty (table 15-). the level of alfalfa weevil
abundance, was very low. Only 2 of 25 fields were inhabited by menac-
ing numbers of weevils and in 10 fields no weevils were found. The
number of living, parasites was also low but they were sufficiently
numerous to be effectiv6,-i"except6'f wT-e 'aTrg6 acreages make cutting
very late.

Table 15.--Survey results. Churchill C0ountSy. Tev. sampled
november 3-5. 1937


Ficld No. : H. postica : B. curculionis cocoons
adults : Present : Viable
: .TuL.* er T I -'-i'ber : "u-ber

1i ----- -0 1.75 50
2 - - - ---- 0 6.00 : 0
3 -- - - - .25 : 10.00 : 1.00
4 - - ----1i.oo 00 15.25 : 1.75
5 - -- .50 : l.5o 0 .25
6----- --- -- ..25.25 : o
7 .25 2.25 .50
g --- ---------.25 : 10.00 .50
9 -0 ------1.0 0
10 - - --- - 1.00 : 37.00 : 2.14
11 - - - - .25 1.50 .50
12 - - - - 2.00 25.25 g9
13 .75 6,25 .75
14 - - - - .25 : 15.75 : o
15 - - - - -2.25 : 13.00 .25
16 ------------- -0 : 16. 25. : 0
17 ------ -.- -- --- .50 4.75 : 0
1 -0 : 1.00 .25
19- 0 2 2.25 .25
20 - - - - 0 .-25 0
21 - - - - -. 0 4.25 .50
22 -------0 50 : 0
23 - - - - -. 0 23.25 : 0
24 - - - .50 4.75 : 0
25 - - .- -. 25 : 10.50 : 1.50
Average -- 041 94 : 0.46


IrgPPSKA

The consistently cold winter of 1936-37, with little protective
snow covering, followed by a cold, damp sprint, prevented development
of weevil injury in Sioux County in 1937. In Sioux County (table 16)


-49-





U UNIVERSITY OF FLRIDA

3 1262 09244 6995


-50-.,


only 1 of 12 fields surveyed was populated by.a potentially injurious
number of weevils. Parasite cocoons were scarce but the high percentage
of them alive indicated effective parasitization for 1938 .. .

Table 16.--Survey results. Sioux County. Nebr., sampled


October 10-12. 1937


Field No. H. postica : B. urculions cocoons
..... adults : Present Viable
Number : Number lu: Nmber

1 ... - o 13.25 5.00
2 0 0 --
- - - - 2.75 4.75 2.25
4 0 50 0
5 ----- .25 --
6 - - - - - ..25 0
- - - 0 :.25 0
7 0 0
8 - - --- 7 -0 : .50 .50
9 - - - - - 1.25 .25 : 0
o10 - - - - 0 1.50 .50
11 - -- - - - .25 1.25 .50
12 - - - 0 .25 0

Average - 0.29 1.88 0.73

OUTLOOK FOR WEEVIL DAMAGE IN 1938

The fall survey of 1937 showed that alfalfa weevil populations
had increased generally'in the infested territory since the fall of 1936.
Most severe damage for 1938 is indicated for Box Elder County, Utah, and
Jackson County, Oreg., where from 40 to 50 percent of the surveyed fields
had damaging numbers of weevils. From 17 .to 33 percent of the fields are
menaced in Salt Lake and Sanpete Counties, Utah, the several.counties con-
stituting the upper Snake River Valley of 'eastern Idaho, Eagle Valley in
Baker County, Oreg., Douglas and Washoe Co6unties, Nev., and Delta and Mesa
Counties, Colo. Damage to approximately 10 percent of alfalfa fields is
indicated for Sevier County, Utah, the lower Snake River Valley of western
Idaho and eastern Oregon, Churchill County, Nov., Montrose County, Colo.,
and Sioux County, Nebr.