APHIS. l6<) 



are also themselves impregnated, and thus the 

 breed may be continued as before mentioned. 



This wonderful faculty in the insects of the pre- 

 sent genus appeared, at its first publication, so 

 extraordinary as to excite no small degree of 

 scepticism in the philosophical world. The ob- 

 servations however of Bonnet, Reaumur, Lyonett, 

 and others have amply confirmed its truth. Lee- 

 wenhoek had long before observed that these in- 

 sects were viviparous. Bonnet, whose observa- 

 tions were continued with the utmost accuracy, 

 assures us that the female Aphides continue to 

 produce their young throughout the whole sum- 

 mer; that the males appear only in autumn; and 

 that the females are at that period oviparous. The 

 ova which are thus deposited during the autumn 

 do not hatch till the succeeding spring. It is 

 however uncertain whether the same individual 

 insects which have produced perfect young during 

 the summer become oviparous during the autumn, 

 or whether the oviparous autumnal ones ever pro- 

 duce living young; the preceding observations 

 relating only to the species at large. 



The Aphides in general are very prolific insects. 

 Reaumur computes that each Aphis may produce 

 about ninety young, and that, in consequence, in 

 five generations, the descendants from a single 

 insect would amount to five thousand nine hundred 

 and four million, nine hundred thousand. 



The Aphides are very prejudicial to many trees 

 and plants by absorbing the juices of the tender 

 shoots and leaves, which latter they cause to 



