176 NDIRECT INJURIES CAUSED BY INSECTS. 



motli {Noctiia frugiperda^ Smith), which feeds upon 

 the main shoot*. 



Next to grain pulse is useful to us both when culti- 

 vated in our gardens and in our fields. Peas and beans, 

 which form so material a part of the produce of the 

 farm, are exposed to the attack of a numerous host of 

 insect depredators ; indeed the former, on account of 

 their ravages, is one of the most uncertain of our crops. 

 The animals from which in this country both these 

 plants suffer most are the Aphides, commonly called 

 leaf-lice, but which properly should be denominated 

 plant-lice. As almost every animal has its peculiar 

 louse, so has almost every plant its ^ecvXi^v plant-louse ; 

 and, next to locusts, these are the greatest enemies of 

 the vegetable world, and like them are sometimes so 

 numerous as to darken the air^. The multiplication of 

 these little creatures is infinite and almost incredible. 

 Providence has endued them with privileges promoting 

 fecundity, which no other insects possess : at one time 

 they are viviparous, at another oviparous ; and, what 

 is most remarkable and without parallel, the sexual 

 intercourse of one original pair serves for all the ge- 

 nerations which proceed from the female for a w hole 

 succeeding year. Reaumur has proved that in five 

 generations one Aphis may be the progenitor of 

 5,904,900,000 descendants ; and it is supposed that in 

 one year there may be twenty generations'^. This 

 astonishing fecundity exceeds that of any known ani- 



^ Smith's Abbott's Insects of Georgia, 191. 



*■ I say this upon the authority of Mr, W'olnoiigh of Alderton (late of 

 Boyton) in Suffolk, an intelligent agriculturist, :vnd a most acute and 

 accurate observer of nature. " Rcauni. vi. 366. 



