what irregular, because of the small numbers of
tests made, all weevils were killed within 6 days. The results indicate
definitely that DDT is toxic to the adults of both species of weevils.
No consistent differences between species were noted.

As the matured nuts dropped from the treated trees, daily collections
were made, and one-third of each collection was used as a sample in
determining the percentage of wormy nuts. At the time the nuts drop, the
holes in the shell through which the eggs were inserted are very
difficult to detect. The nuts were therefore held in wire baskets to
permit most of the larvae to emerge before the final examination. All
nuts not showing exit holes were cut open to find out whether they were
wormy. The marked increase in clean nuts after all treatments indicates
that DDT is a promising insecticide for use against the weevils. The
treatment and infestation records for the sprayed trees and the check
tree are given in Table 3, which also includes the results obtained in
later years.

+Spray Experiments 1945 to 1947+

Spring frosts in 1945 destroyed 95 per cent of the crop of chestnuts in
the Eastern States. Only six trees of different species and ages in the
Government orchard at Glenn Dale, had sufficient nuts for experimental
purposes. Applications of a 50 per cent DDT wettable powder in the
proportions of 4 and 6 pounds plus 1/2 gallon of summer oil as a sticker
to 100 gallons of water were made on August 20 and September 9.

Spring frosts again damaged the orchards in 1946, destroying about 80
per cent of the possible chestnut crop, and leaving only eight trees in
the Government orchard that were suitable for experimental purposes. The
remaining trees having a small scattered crop were disregarded. A
mixture consisting of equal parts by weight of DDT and kaolin 41 was
used in the strength of 2 pounds of DDT to 100 gallons of water. The
time and number of applications were varied.

Table 3. Results of spray tests with DDT against chestnut weevils,
1944-1947.

Larvae Emerging from Sample
Reduction
Nuts Small Large Wormy of
DDT (per Application in Chestnut Chestnut Nuts Injured
100 gal.) Sample Weevil Weevil Nuts
Year
Pounds Number Number