ORCHARD INJURY BY HICKORY TIGER-MOTH. 9 
The larve reared in 1915 passed through only 8 instars, but the 
majority of those reared in 1916 passed through 9 instars. This 
could not have affected greatly the time required for development, 
however, as the few larve which passed through only 8 stages in 
1916 required an average of 88.71 days. In 1915 the larve were 
reared under natural conditions in bags on a tree, whereas in 1916 
all lots but one were reared in battery jars. The one lot of 22 larve 
reared on the tree in 1916 required from 85 to 92 days from ege to 
cocoon, with an average of 87.18 days, very nearly the same as that 
of those reared in confinement. : 
No explanation is offered for the difference in time required for 
development of larvee in the two seasons, but it should be stated 
that the season of 1915 was excessively rainy, whereas the 1916 sea- 
son was excessively dry. It is probable that humidity affected the 
rate of development either directly or by its effect upon the food 
plant. 
The duration of the larval feeding period varies somewhat when 
different food plants are used. The development of those reared on 
apple was similar to that on walnut, but a little slower, and the 
larvee passed through only 8 stages. The shortest period required 
for development from egg to cocoon was 89 days and the longest 
was 96 days, with an average of 92.87 days. 
Pear seemed a slightly more favorable food plant than apple. The 
development of the larve was more rapid, and although the majority 
passed through only 8 stages a few passed through 9 stages. Eight- 
een larvee which passed through 8 stages required from 87 to 91 
days, with an average of 88.77 days; 5 larvee which passed through 
§ stages required from 98 to 100 days, averaging 98.40 days. 
The duration of the stages of larve reared on Japanese walnut 
during the season of 1916 was as follows: 
First stage: Minimum 6 days, maximum 7 days, average 6.12 days; 232 
larvee reared. 
Sccond stage: Minimum 4 days, maximum 7 days, average 4.78 days; 232 
larvee reared. 
Third stage: Minimum 5 days, maximum 7 ae average 5.62 days; 232 
larvee reared. 
Fourth stage: Minimum 6 days, maximum 7 days, average 6.02 days; 232 
larvee reared. 
Fifth stage: Minimum 6 days, maximum. 8 days, average 6.25 days; 232 
larve reared. 
Sixth stage: Minimum 6 days, maximum 13 days, average 8.52 days; 145 
larve reared. 
Seventh stage: Minimum 8 days, maximum 20 days, average 12.33 days; 145 
larvee reared. 
Highth stage (excluding larve that completed their feeding period in this 
stage) : Minimum 13 days, maximum 25 days, average 18.03 days; 138 larvze 
reared, 
