rfax, Va. Aug. 26 35 9 1 29
Sept. 10 58 25 4 50
Sept. 28 50 35 7 84
Oct. 7 217 177 22 92
Elkton, Md. Aug. 21 139 11 13 17
Sept. 4 83 22 25 57
Sept. 18 116 21 35 48
Oct. 1 108 31 44 69

+Spray Experiments in 1944+

Shortly after adults of the large chestnut weevil first appeared in the
orchards in 1944, six trees isolated from other chestnuts were selected
for treatment. Five trees were sprayed with from 1 to 5 pounds of
technical DDT plus 1/2 pound of sodium lauryl sulfate to 100 gallons of
water, and the sixth tree was left untreated as a check. A thorough
application of a coarse, drenching spray at a pressure of 400 pounds per
square inch was used in an attempt to force the DDT between the many
spines of the burs. The DDT used was very coarse, and difficulty was
experienced in getting a proper suspension. This formula was used,
however, in preference to one which contained other ingredients that
might have formed a protective coating over the particles of DDT. Heavy
rains prevented later spray applications.

Adult weevils obtained by jarring untreated trees were then confined in
screen cages placed over the lower branches of the trees. At the end of
each cage was a cloth sleeve which was tied to the limb to hold the cage
in place. The treatments used and the results are given in Table 2.

Table 2. Percentage mortality of chestnut weevils placed in field cages
on trees at different intervals after they had been sprayed with with
DDT, 1944.

Strength of
DDT (lb. per Small Chestnut Weevil Large Chestnut Weevil
100 gal.) 48 Hrs. 96 Hrs. 144 Hrs. 48 Hrs. 96 Hrs. 144 Hrs.

1 0 61 100 25 50 100
2 19 69 100 0 34 100
3 4 50 100 0 40 100
4 27 87 100 0 50 100
5 18 50 100 30 46 100
Check 0 0 0 0 7 7

Although the results obtained the first few days in the cages containing
treated foliage were some