366 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
eggs failing to hatch. The data of these tests showed, in addition, that 
the efficiency of all insecticides varied directly with the time following 
deposition at which the application was made. Records indicate an 
even gradation from 87.95 per cent failing to hatch with application 
on the day of deposition to 55.78 per cent failing to hatch with applica¬ 
tion just prior to hatching. 
Table I. —Results with Nicotine and Nicotine Combinations in Laboratory Tests with 
Selected Eggs and Just-Hatched Larv.e of Laspeyresia molesta Btisck, Leesburg, 
Virginia, 1919 
Total 
number 
of eggs 
employed 
Total number 
Per cent 
Insecticide 
Formula 
of eggs not hatching, 
(and in arsenical combinations) 
larvae dead 36 hours after 
hatching 
1. Arsenate of lime, powder. 
Nicotine sulphate (40%). 
Sea moss. 
§-50 
1-800 
4-50 
44 
44 
100.00 
2. Nicotine sulphate (40%). 
Sea moss. 
1-800 
4-50 
587 
560 
95.40 
3. Arsenate of lead, paste. 
Nicotine sulphate (40%). 
Calcium (3), casein (1). 
2-50 
1-800 
1-50 
353 
296 
83.85 
4. Arsenate of lime, powder. 
Self-boiled lime sulphur. 
Nicotine sulphate (40%). 
Sea moss. 
§-50 
8-8-50 
1-800 
4-50 
62 
41 
66.12 
5. Nicotine sulphate (40%). 
Calcium (3), casein (1). 
1-800 
1-50 
484 
257 
53.08 
A study of selected unsprayed egg£ as check showed that only 8.9 per cent failed to hatch. 
Tests with Single Caged Peach Trees in an Orchard 
Equally encouraging results have been obtained in limited field 
tests, in which applications were made to two-year-old infested peach 
trees enclosed in cages. These trees, from three to four feet in height, 
had been pruned back well, resulting in an abundance of growth and 
foliage, which proved an attractive feeding-ground for the first brood 
larvae of the moth. On June 23, after cessation of feeding by second 
brood larvae, a count was taken of the total number of twigs per tree, 
also the total number of injured twigs per tree. The percentage of in¬ 
jury based on these counts is given in Table II. 28.34, the average 
per cent of injury for the entire plot corresponds very nearly with the 
amount of injury usually found in infested peach trees throughout the 
infested area of northern Virginia. On June 14, while egg-laying was 
in progress, applications were made of several insecticides, the results 
with nicotine and nicotine combinations only being included here. 
