36 ANNUAL REPORT OF NEW YORK 
in this state they were buried beneath the snows of winter, and with the 
warmth of the ensuing spring they were thawed, and returned to life again. 
To be better assured upon the subject, I placed some of these insects on 
grain growing in flower-pots and kept during the winter in a warm room. 
In this situation they continued alive and continued to bear young through 
the whole winter season. 
Thus I have watched this grain aphis this year round, so closely, that I 
am perfectly assured no eggs were laid and no males were produced. 
Occasionally an individual was noticed, varying somewhat from the others, 
and which I have therefore suspected might be a male; but, on imprison¬ 
ing such specimens in vials over night, I have invariably found young 
lice with them next morning. 
When, and under what circumstances males occur, if they ever do occur, 
is yet remaining to be discovered. At present it Seems as though these 
insects might go on forever, producing young, without any intercourse of 
the sexes. 
Finally, with regard to the fecundity of these insects, I would state that 
those which have no wings, and which remain on the stalks of grain on 
which they are born, are much more prolific than those which have wings 
and wander abroad. By inclosing them separately in vials, I found the 
winged females quite uniformly gave birth to two young lice in a single 
night, whilst the wingless ones produced four in the same time. We fre¬ 
quently see young lice produced in the day time, but fewer appear to be 
born then than during the night. The winged ones are also much slower 
in coming to maturity. I placed several young lice the morning after they 
were born upon some grain growing in a flower-pot, and on the third morn¬ 
ing afterwards I found four little ones around each of them, showing that 
the wingless ones come to maturity in three days. It will thus be seen 
with what prodigious rapidity these creatures multiply. They almost 
double their numbers daily. A single one producing four young daily, 
and these becoming equally prolific when they are three days old, her 
descendants in twenty days, if all live, will number upwards of two 
millions. This will serve to explain to us how it is that this insect becomes 
so excessively numerous upon the grain at harvest time, as we have 
seen it. 
As they multiply so rapidly, it is evident no vegetation which they infest 
would escape destruction from these plant lice, if nature had not herself 
provided most efficient means for checking and subduing them. We 
accordingly find that these insects are preyed upon and consumed by other 
insects, to a greater extent than are any other kinds of injurious insects 
wherewith we are molested. There are whole groups and tribes of pre¬ 
daceous insects which subsist exclusively upon the plant lice of different 
kinds. 
A tribe of very small Ichneumon flies, named Aphidius, are parasitic 
destroyers of these insects — puncturing and thrusting an egg into the body 
of the aphis, from which hatches a minute worm which feeds within the 
aphis till it kills it. I have found two species of these parasites destroy¬ 
ing the grain aphis. 
Another most efficient destroyer is the lady bug or coccinella, of which 
