94 THE PESTS OF THE FARM. 



PLANT LICE. The Aphidians, in which group we include the 

 insects commonly known by the name of plant-lice, differ remark- 

 ably from all the foregoing in their appearance, their formation, and 

 their manner of increase. Their bodies are very soft, and usually 

 more or less oval. 



Aphides, or plant-lice as they are usually called, are among the 

 most extraordinary of insects. They are found upon almost all 

 parts of plants, the roots, steins, young shoots, buds, and leaves, 

 and there is scarcely a plant which does not harbor one or two 

 kinds peculiar to itself. They are, moreover, exceedingly prolific, 

 for one individual, in five generations, may become the progenitor 

 of nearly six thousand millions of descendants. It often happens 

 that the succulent extremities and stems of plants will, in an in- 

 credibly short space of time, become completely coated with a liv- 

 ing mass of these little lice. These are usually wingless, consisting 

 of the young and of the females only ; for winged individuals ap- 

 pear only at particular seasons, usually in the autumn, but some- 

 times in the spring, and these are small males and larger females. 

 After pairing, the latter lay their eggs upon or near the leaf-buds 

 of the plant upon which they live, and, together with the males, 

 soon afterwards perish. 



The winged plant-lice provide for a succession of their race by 

 stocking the plants with eggs in the autumn. These are hatched 

 in due time in the spring, and the young lice immediately begin to 

 pump up sap from the tender leaves and shoots, increase rapidly in 

 size, and in a short time come to maturity. In this state, it is found 

 that the brotxl, without a single exception, consists wholly of fe- 

 males, which are wingless, but are in a condition immediately to 

 continue their kind. Their young, however, are not hatched from 

 eggs, but are produced alive, and each female may be the mother 

 of fifteen or twenty young lice in the course of a single day. The 

 plant-lice of this second generation are also wingless females, which 

 grow up and have their young in due time ; and thus brood after 

 brood is produced, even to the seventh generation or more, without 

 the appearance or intervention, throughout the whole season, of a 

 single male. This extraordinary kind of propagation ends in the 

 autumn with the birth of a brood of males and females, which in 

 due time acquire wings and pair ; eggs are then laid by these fe- 

 males, and with the death of these winged individuals, which soon 

 follows, the race becomes extinct for the season. 



The peach-tree suffers veiy much from the attacks of plant-lice, 



