Insects Bred from American Larch 45 
Minimum number of egg niches in egg gallery........... 1 
Maximum number of egg niches in egg gallery Ayo cesta, sheke ats 53 
Average number of egg niches in egg gallery. LOB ae SHOT, 20.84 
Average number of egg niches in uniramous gallery...... 29.4 
Average number of egg niches in biramous gallery....... 25.36 
Average number of egg niches in triramous gallery...... 18.52 
Average number of egg niches in quadriramous gallery... 16.10 
Average number of egg niches in quinquiramous gallery.. 14.3 
It would seem from the above that each female produces 
a larger number of eggs when her mate serves no other 
females, 7. e., under conditions of monogamy. However, in 
order to get at what might be styled the individual efficiency 
the total number of eggs in all the egg-galleries of the burrow 
should be divided by the total number of individuals (male 
and females) in the burrow. The following results then 
appear: 
Eggs per 
Number of eggs Male Females Individual 
29.4 = (1 + 1) = 14.7 
50.72 a (1 + 2) = 16.91 
55.56 = (1 + 3) = 13.89 
64.40 =z (1 4- 4) = 12.88 
71.5 = (1 -- 5) = 11.91 
Thus the following facts appear: The greater the number 
of females in a burrow, the greater is the total average num- 
ber of eggs per burrow but the less per individual “female. 
Under average conditions the males outnumber the females in 
the ratio of two and one-half to one and the greatest reproduc- 
tive efficiency is shown in burrows containing one male and 
two females. Should the sexes occur in nature in equal num- 
bers the greatest efficiency would be shown in burrows having 
one of each sex, for then each female on an average would 
deposit 29.4 eggs although the individual efficiency is only 
half that amount; while in a biramous burrow each female 
lays, on an average, 25.36 eggs, but the individual reproduc- 
tive power is greater than in the former case. However, if 
in nature the females should outnumber the males at the 
ratio of four to one or five to one the greatest number of 
eggs would be produced by their breeding in the same ratio. 
