136 
Journal of Agricultural Research 
Vol. XXI, No. 3 
are found on the surface of the terminal twigs, but always close to the 
late needle growth. Wherever found they are not securely attached. 
(PI. 29, B.) 
PERIOD OP INCUBATION 
Incubation lasts approximately from 12 to 14 days. The maximum 
time required for the eggs to develop, as recorded in the season of 1919, 
was 14 days, the minimum 12 days, and the average 13 days. Records 
on the incubation of eggs for the season of 1919 are given in Table III. 
Table III .—Incubation period of eggs of Recurvaria milleri, season of igiQ 
Number 
of eggs 
in 
record. 
Date of 
depo¬ 
sition. 
Date of 
hatching. 
Incuba¬ 
tion 
period. 
5 
July 27 
Aug. 8 
Days. 
12 
3 
27 
9 
13 
1 
30 
13 
13 
4 
30 
14 
14 
THE LARVA 
DESCRIPTION 
The mature larva is roughly cylindrical; its average length is 8 mm., 
or from seven to nine times the width. The color varies from light 
lemon yellow to deep orange, with an indistinct darker red patch along 
the dorsal median line. The head is black with dark brown thoracic 
shield, and the anal plate is lighter brown. The prolegs are on the 
sixth, seventh, eighth, and ninth abdominal segments. 
HABITS OP LARVAE 
The larvae feed on the interior of the needles by boring in near the 
outer ends and working toward the bases, constructing longitudinal 
mines which vary in length from one-third to the entire length of the 
needles (PI. 29, C). The frass and excrement are ejected through the 
entrance hole as fast as accumulated. The larvae are very active; when 
disturbed they retreat through the needle mines, backing out through 
the entrance holes, and occasionally letting themselves down by means 
of a thread spun from the silk glands. 
The first stages of the larvae are passed in the young needles of the 
current year’s growth. The first winter is also passed in these needles. 
When the needles of the next crop arrive the following summer the 
larvae migrate to them and feed until the dormant period of the second 
winter begins; the second hibernation occurs in these needles. When 
activity is resumed the second spring the larvae complete the mining of 
the needles in which the winter was passed and enter fresh needles of the 
