14 BULLETIN 1182, U. S. DEPARTMENT OF AGRICULTURE. 
Table 7. — Life chart {average) of Diprion simile. 
Progeny of adults issuing in the spring. 
Progeny of adults 
ssuing in summer. 
Period. 
Adults emerging 
same year as co- 
cooning. 
Adults emerging 
the next year 
after cocooning. 
Adults emerging 
same year as co- 
cooning. 
Adults emerging 
next year after 
cocooning. 
Male. 
Female. 
Male. 
Female. 
Male. 
Female. 
Male. 
Female. 
Incubation period 
Days. 
12.8 
Days. 
12.8 
Days. 
12.8 
Days. 
12.8 
Days. 
8 
Days. 
8 
Days. 
8 
Days. 
8 
Larval period: 
First stage 
6 
4S 
4f 
8 
7 
4 
44 
24 
5 
94 
6 7 
4 
5 
2 
3 
2 
4 
5 
2 
3 
2 
Second stage 
4J 
8 
4 
44 
24 
5 
94 
Third stage 
Fourth stage 
Fifth stage 
6 
Total 
28 
10 
5.8 
32 
10 
7.5 
28 
341 
5.8 
32 
341 
7.5 
16 
i 18 
16 
295 
5.8 
i 18 
Prepupa (including 
pupal period) 
29 29 
5. 8 7. 5 
295 
7.5 
Total 
56.6 
62.3 
387.6 
393.3 
58. 8 62. 5 
324.8 
328.5 
1 Obtained by rule of proportion, as no isolation for length of larval stages gave female adults. 
The accompanying chart (Fig. 7) gives a general view of the activities 
of this species covering a period of about four years, especially the 
relations existing between stages, broods, generations, and colony 
periods, and shows the possible opportunities of the species to inbreed 
and crossbreed among the various colonies, broods, and generations. 
EFFECT OF METEOROLOGICAL CONDITIONS. 
The notes on the effects of meteorological conditions on this species 
are incomplete and do not lead to any definite conclusions with 
regard to the part climate will play in its establishment or in the 
restriction of its range in America. The small number of adults 
obtained in the rearing experiments undertaken under the life- 
history, seasonal-history, and host-plant work gives the impression 
that the climate of the section of the country where this work was 
undertaken, East Falls Church, Va., near Washington, D. C, is 
rather unfavorable for Diprion simile, while the apparent establish- 
ment of the species in New England, New York, and New Jersey 
points to the suitability of a somewhat cooler climate. 
In the cage work, where the rapidity of development was noted, 
it was observed to be accelerated by increased temperature. 
Table 8 records the duration of stages and instars in clays for two 
colonies of Diprion simile between which there was a difference of 
46 days in the date of egg laying, and shows the average temperature 
during each of the stages or instars. 
