APHIS. 173 



insects. Yet Mons r . 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 which 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 



