May 2,1921 
Life History of Recurvaria milleri 
137 
same growth. When these are partially or completely mined the now 
mature larvae prepare pupal cells in the last-mined needles and envelop 
themselves in thin silk. During its life each larva mines an average of 
three needles. (Fig. 1.) 
LENGTH OF LARVAL STAGE 
The maximum length of the larval stage is 23 months, or from August 
15 of the first year to July 1 of the third year (Table IV). 
Table IV .—Duration of the larval stage of Recurvaria milleri 
Date of observation. 
Development and activity of larvae. 
Aug. 15,1917, to June 
I, 1918. 
June 4, 1918. 
June 13, 1918. 
June 22, 1918. 
July 13, 1918. 
July 20, 1918. 
Aug. 5, 1918. 
Aug. 12, 1918. 
Aug. 23, 1918, 
Sept. 4, 1918. 
Sept. 15, 1918. 
Sept. 16,1918, to May 
24, 1919. 
May 24, 1919. 
June 1, 1919.. 
June 10, 1919 
June 25, 1919 
July 10, 1919. 
July 25, 1919. 
No observations were recorded for this period . 1a 
Larvae 3 mm. long; feeding in needles of 1917 growth. 
Larvae 3.5 mm. long; feeding in needles of 1917 growth. 
Do. 
Larvae 4 mm. long; feeding in needles of 1917 growth. 
Larvae 5 mm. long; feeding in needles of 1917 growth. 
Larvae in mined needles of 1917 growth and entering unmined 
needles of 1918 growth. 
Larvae in mined needles of 1917 growth and entering unmined 
needles of 1918 growth; many larvae in migration exposed 
on foliage. 
Larvae in mined needles of 1917 growth and entering unmined 
needles of 1918 growth; only a few individuals remaining in 
mined needles of 1917 growth. 
Larvae 5.5 mm. long; all in needles of 1918 growth. 
Do. 
No observations were recorded for this period. 0 
Larvae 6 to 7 mm. long; in mined needles of 1918 growth. 
Larvae migrating from mined 1918 needles to unmined 
needles of same growth. 
Do. 
Larvae 7 to 8 mm. long; in freshly mined needlesof 1918 growth. 
Prepupal larvae and pupae in mined needles of 1918 growth. 
Do. 
Do. 
® The absence of records for these periods is due to the author’s absence from the park. 
THE PUPA 
DESCRIPTION 
The pupae are dark brown to black in color and are approximately 
1.2 mm. in diameter by 6 mm. long. They are found in thin silk cocoons 
in the last needles mined by the larvae. (PI. 29, C.) 
LENGTH oe pupal STAGE 
The maximum pupal stage lasts from June 20 to July 20, or 30 days. 
HOST PLANT 
These studies were confined exclusively to the Yosemite National 
Park, Calif., wherein the insect was found attacking only one host tree, 
the lodgepole pine (Pinus murrayana). 
