INJURING THE TRUNK. 



73 



and June by small, shining black plant-lice, that 

 suck out the sap and deform the leaves. This insect 

 is the Cherry Aphis. The wingless form is repre- 

 sented much magnified at a, Fig. 31, and the winged 



a b 



Fig. 31. Cherry Aphis: a, wingless female ; 6, winged female. Magnified. 



form at b of the same figure, the straight lines at the 

 right indicating the natural size. 



The Cherry Aphis winters over on the twigs in the 

 egg state. Early in spring the eggs hatch into young- 

 aphides that crawl upon the bursting buds, inserting 

 their tiny sap-sucking beaks into the tissues of the 

 unfolding leaves. In a week or ten days they become 

 full grown, and begin giving birth to young lice, 

 which also soon develop, and repeat the process. In 

 this way they increase with marvellous rapidity. 

 Most of these early spring forms are wingless, but 

 during June great numbers of winged lice appear, 

 and late in June or early in July they leave the 

 cherry, migrating to some other plant, although we 

 do not yet know what that other plant is. Here they 



