8 BULLETIN" 1182, U. S. DEPARTMENT OF AGRICULTURE. 
into a period early in the year and a period late in the year. The 
adults are separated into Brood A. those issuing in the first emer- 
gence period following cocooning, and Brood B, those issuing in the 
second emergence period following cocooning. 
The early emergence period occurs from April to June and is not 
distinctly separated from the later emergence period, which occurs 
during July and August. The rearing cages, however, show a marked 
decrease in the number of adults coming from cocoons duringJJune. 
The following summary of records of the issuance of adults shows 
the duration of this period and its tendency to divide into two parts, 
the months of maximum emergence being April, May, and July. 
Larvse and pupae collected in August, 1915: 
1 adult emerged in August, 1915. 
77 adults emerged in May, 1916. 
5 adults emerged in June, 1916. 
1 adult emerged in July, 1916. 
Cocoons collected in April, 1917: 
16 adults emerged in April, 1917. 
95 adults emerged in May, 1917. 
2 adults emerged late in June, 1917. 
2 adults emerged in July, 1917. 
1 adult emerged in April, 1918. 
Larvae cocooning in June of various years: t 
2 adults emerged in June of the same year in which they cocooned . 
24 adults emerged in July of the same year in which they cocooned. 
1 adult emerged in August of the same year in which it cocooned. 
7 adults emerged in April of the year following that in which they cocooned. 
8 adults emerged in May of the year following that in which they cocooned. 
LONGEVITY OF ADULTS. 
The average length of life for adults of Di prion simile was 6.6 days, 
with a range from 3 to 11 days. The life of the female was slightly 
longer than that of the male, the former averaging 7.5 days, with a 
range from 5.5 to 11 days, while the latter averaged 5.8 days, with a 
range from 3 to 9 days. The life of female adults known to have 
laid eggs was somewhat longer than the life of those not known to 
have laid eggs. Females laying eggs averaged 7.75 days, those not 
known either to have laid eggs or not to have laid eggs averaged 
7.66 days, while those known not to have laid eggs averaged 7 days. 
The two shortest-lived males were the progeny of parthenogenetic 
females. Only two of these were available for this study, and these 
lived, one 3 and the other 4 days. 
PROPORTION OF SEXES. 
The males seem somewhat to exceed the females in number, and 
from a series of 227 adults issuing from cocoons in certain of the cages, 
134, or 59 per cent, were males, while 93, or approximately 41 per 
cent, were females. 
MATING. 
Mating was not observed. At different times three males were 
caged in glass vials with a single unfertilized female without their 
paying her the slightest attention. This, however, was probably 
due to the close confinement of the sawflies under observation, 
which tended to distract them and prevent or discourage natural 
behavior. The fact that from the life-history and seasonal-history 
