PLANT-LICE. 



263 



occur. The wingless forms are generally asexual, and so are 

 the summer winged females. Winged males and oviparous 

 females also occur. Ova are usually laid only in the autumn 

 by the oviparous female after fertilisation by the male. The 

 tarsi are of two segments, and the wings contain very few 

 veins, by which the Dolphins, as they are called in Kent, are 

 partly classified. The reproductive powers of these insects are 

 enormous as well as peculiar. The wingless female, starting in 



Fir;, 151. — Cherry Aphis {Myzus ceran). 

 u. Winged $ ; 6, apterous 9 . 



the spring, produces with great rapidity living young without 

 the agency of a male ; these asexually produced young or lice 

 soon grow sufficiently to start reproducing again, and so on 

 for eight or nine generations. As a rule, a plant becomes 

 smothered by these wingless forms ; and in the summer some 

 send out little bud-like growths from the thorax, rudimentary 

 wings, a pupal stage, and from these active pupae come forth 

 winged females, which fly off to other plants. These winged 

 females are also viviparous, and produce again asexually living 



