106 
Walton, of this bureau, observed a larva, taken from the body of a 
"green bug," to apparently feed upon another larva of the same species 
that was resting against it. Tins would seem to indicate a tendency 
toward cannibahsm. The parasites have been observed apparently 
ovipositing in aphidids that were already dead from parasitic attacks, 
those killed by fungus, and sometimes even puncturing the leaves 
of the plants on which Toxoptera were located. 
The period of oviposition varies from 3 days to a week or more, 
depending upon the temperature. In warm weather the females will 
easily live and oviposit for 5 or 6 daj^s. 
LENGTH OF PERIOD FROM EGG TO ADULT. 
Messrs. Kelly and Urbahns found that at Wellington, Kans., from 
7 to 15 da} r s are consumed in passing from egg to adult during 
August and September, while for October and the first week in 
November it requires from 8 to 24 days. These figures are to a slight 
degree artificial, as the rearings upon which they are based were 
conducted indoors. The room was heated by a stove, during the day 
only, for a part of October and November, and all fire was extin- 
guished at night, so that the temperature at night probably went 
almost as low as out of doors, the house being only a small two- 
room structure. 
The average for August and September is 11.1 days; the average 
for October and November (first week) is 19 days, the average for 
the whole period being 15.9 days. These averages were made up from 
observations on 116 individuals and are therefore of more value 
than they would be if made from a few individuals only. 
At Richmond, Ind., the period from egg to adult out of doors varies 
from 10 to 14 days during August and September, while Toxoptera 
that were parasitized during November of 1907 and kept out of doors 
did not give up adults until the 27th and 28th of March and the 4th of 
April, 1908, a period of over 4 months. 
EFFECT OF PARASITISM BY APHIDIUS UPON DEVELOPMENT OF HOST. 
It has been found, as previously stated, that at no time from birth 
to and including the adult stage is Toxoptera exempt from attack by 
Aphidius. It appears that a female Aphidius prefers to oviposit in 
Toxoptera of the second and third instars. The parasite apparently 
shows little or no fear of them at this stage, while if she is among a 
number of adult Toxoptera and they begin to kick up their abdomens, 
she often hurries away, apparently in alarm. 
It appears from our observations that Toxoptera stung before the 
first or second molt will not reach maturity, nor mil the developing 
parasite become adult, there being apparently insufficent nourish- 
ment contained in such small individuals. Aphidids parasitized after 
