178 INJURIOUS INSECTS. 



of our very large and busy manufacturing towns. I shall be glad to find 

 cither a confirmation or modification of my statements in future numbers 

 of "The Naturalist/' from various correspondents. 



The Elms, Moseleij Road, Birmingham, May 28^A., 1856. 



INJURIOUS INSECTS.— No. VI. 

 APHIS; APHIDES, OR PLANT-LICE. 



BY J. MC'INTOSH, ESQ. 



C Continued from page 31. J 



"The insect pest, powerful though small, 

 Blighting at ouce the green leaf and the grain." 



Graham. 



The Aphides, or Plant- Lice belong to the seventh order, Hemiptera. 

 These minute but destructive insects, which compose this numerous genus 

 are exceedingly annoying and destructive to the produce of the cultivator 

 of the soil, infesting almost every plant he cultivates as food, and many 

 of our wild ones, as well as our trees, stopping their growth by con- 

 suming their juices. They are a most singular race of insects, living in 

 large societies, being winged and apterous. In spring they are viviparous, 

 producing their young alive at the rate of twenty-five or more a day. In 

 the autumn they are oviparous, which appear destined to perpetuate the 

 species, as the eggs live through the winter, while the individuals perish. 

 Nor is this all, for by a surprising deviation from the common laws of 

 Nature, it appears from the writings of Bonnet, Reaumur, Latreille, Lyonnet, 

 De Geer, Linne, and others, that one impregnation of the female is suf- 

 ficient for many successive generations, without the further assistance of the 

 male. Bonnet, who appears to have studied these insects with more atten- 

 tion than any other writer, asserts that he has witnessed the birth of nine 

 generations in three months from one impregnation; and Reaumur has also 

 proved that in five generations one Aphis may be the parent of the as- 

 tounding number of five thousand nine hundred and four millions, nine 

 hundred thousand descendants, and it is supposed that in one year there 

 may be twenty generations. 



"This astonishing fecundity exceeds that of any other known animal, and 

 we cannot wonder that a creature so prolific should be proportionably inju- 

 rious. Some species are more so than others. Those that attack wheat, 

 oats, and barley, of which there are more kinds than one, seldom multiply 

 so fast as to be very noxious to those plants; whilst those which attack 

 pulse, spread so rapidly, and take such entire possession, that the crop is 

 greatly injured, and sometimes destroyed by them. This was the case with 



