APHIS. 
173 
insects. Yet Mons^ Bonnet, who may be said to 
have almost taken up his abode with these insects, 
informs us that he has frequently noticed such 
connexion, which he describes as taking place at 
one certain time of the year only; and that from 
a female thus impregnated, many successive gene- 
rations will be produced without any farther im- 
pregnation. He took the Aphides as soon as 
brought forth, and kept each individual separate. 
The females of such brought forth abundance of 
young. He took the young of these, and treated 
them precisely in the same manner. The produce 
was the same: and thus he proceeded to the ninth 
generation with the same success ; and so far from 
considering that as the utmost extent of the effect, 
he thinks it might be carried on to the thirtieth 
generation. In most species of Aphides, both 
males and females acquire wings at certain sea- 
sons; but in this respect they are subject to great 
variation, there being some males and some females 
that never have wings; again there are some fe- 
males that become winged, while others of the 
same species do not. In the quality of the excre- 
ment voided by these insects there is something 
very extraordinary. Were a person accidentally 
to take up a book in vvdiich it was gravely asserted 
that in some countries there were certain animals 
which voided liquid sugar, he would soon lay it 
down, regarding it as a fabulous tale, calculated 
to impose on the credulity of the ignorant; and 
yet such is literally the truth. The superior size 
of the Aphis salicis will enable the most common 
