16 BULLETIN 766, U. S. DEPARTMENT OF AGRICULTURE. 
The pupa stage of Compsilura is passed in two ways. In the 
field, puparia will be found both in the crevices of the bark and in the 
webs of prepupal brown-tail moth larve or “spin-ups.” They will 
also be found about 1 inch beneath the surface of the soil at the 
base of trees. The average length of the pupa stage in the soil is 
from two to four days greater than above ground. 
ADULT STAGE. 
The length of the adult stage under laboratory conditions varies 
with the temperature and methods of handling. The methods of 
handling have been previously mentioned. The average length of: 
the adult stage of Compsilura is shown in Table IV. 
‘TasBLe LY.—<Average length of adult stage of Compsilura concinnata, HBSS 
Highlands, Mass., 1916. 
22 days for 35 mated males in glass-covered trays. 
18 days for 35 mated females in glass-covered trays. 
13.5 days for 22 unmated males in glass-covered trays. 
4.5 days for 22 unmated females in glass-covered trays. 
GESTATION. 
The period of gestation varies with the temperature, an increase in 
temperature tending to shorten the period. A new supply of hosts 
was added every two days and close watch for the emergence of Comp- 
silura larvee was maintained. The time required for the period of 
gestation was reckoned from the time of mating to the time the 
adults and hosts were separated; then, to get accurately the length of 
the larva stage, each maggot was isolated as it emerged from the host. 
and the larva stage was reckoned from the end of the period of 
gestation. (See Table V.) 
~ Taste V.—Gestation period of Compsilura concinnata: Single females in each 
experiment, Melrose Highlands, Mass., 1916. 
Number 
Average 
Date experiment mee of fly| of Comp- length of} Number and stage Host Sea Se 
began. See De eee larva of hosts. eee Ap 
lation. larve stare period. 
secured. Be. 
Days. Days Days 
Fulkyalon see 1 9.5 | 30, fourth stage....| Brown-tail moth larve. . 4.5 
ESSERE 2 13 1-425| 70; fourth stages a ls.02 20 OS oe eo ee 5 
1 A ee 2 8 7.23 | 60, fourth stage....|....- G0 e252 Ae Sa 3 
By eae ee 2 1 10 70, fourth stage....|..--- GOs. aaaoe Cee 6 
ACVeTages. 3.2 ios ed echoes cece aaa eae SES Sa os Sa ee ee eee ease 4.5 
- PARTHENOGENESIS. 
Since it was thought that Compsilura might, at times, be par- 
thenogenetic, a series of experiments was conducted to determine 
whether this is the case. In each case 5 unfertilized females were 
