454 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
outside of windows where they had evidently been attracted by the heat 
radiating from within. 
Mating has not been observed and is evidently either a very short or a 
nocturnal operation. It is of interest to note that copulation does take 
place, as is proven by the hatching of the eggs, in such a limited space 
as that under an inverted petri plate. 
Records of the preoviposition period were secured in three instances. 
Two of these were three and the other was of four days in length. The 
individuals making these records are shown in Table I. 
The place of oviposition in both the field and the laboratory has already 
been discussed. The following egg-laying records were secured from 
females confined under petri dishes. 
No. A 
“ B 
“ C 
Table III. —Egg Records of Micromus posticus. 
Totals 
000 38 68 0 0 0 0 0 Dead. 106 
0 0 0 0 21 19 31 11 0 0 “ Dead 82 
0 0 0 0 18 12 42 46 21 18 3 16 3 13 34 8 6 2 0 246 
Average 144 
Table III gives a difference of from eighty-two to two hundred and 
forty-six eggs per female with an average of one hundred and forty-four 
each. The period over which the eggs were laid is of interest, in one case 
lasting only two days while in another it extended over two weeks. 
The number of eggs laid indicates that the insect has fair reproductive 
powei s and but for weak spots at other points in the cycle would be much 
more common. 
Observations made on the feeding of the adult seems to indicate that 
the iate is little higher if any than in the case of the third instar larvae 
where the number of aphids destroyed daily averaged about ten. 
The following table deals with the length of life in the adult. 
Table IV. —Length of Adult Life 
Adult No. 1 2 3 4 5 6 7 8 9 10 11 12 13 
Days Alive... . 8 14 21 35 35 36 32 32 10 11 19 6 10 
From the above we find that the average length of life was twenty- 
one days. All the above individuals were reared in captivity during 
the months of August and September. It can only be guessed that adults 
in the open live for a longer time but it is probable that they do. 
In the spring adults have been noted on aphid infested white pine 
during the month of April. Table I shows that the peiiod from egg to 
egg may be passed over in twenty days. If we consider the breeding 
season as lasting from May until October we have a possibility of four, 
five or even more generations. The number of generations combined 
with the reproductive ability of the females should produce a large 
