INSECTS INJURIOUS TO THE APPLE AND PEAR 601 



generations. Those which are to become winged may be dis- 

 tinguished after the third mo'.t by the blackish wing-pads at 

 the sides of the body. With the first frosts of fall the young 

 develop into true males and females. Both are wingless, the 

 male being much the smaller, has long antennae, is yellowish or 

 rusty-brown, and is very active, while the female is larger, moves 

 more slowly and is lighter in color, but later becomes a very 

 dark green. The sexes mate and the females lay 1 to 3 eggs in the 

 places mentioned. All of the aphides die by late fall and the 

 eggs remain to give rise to new colonies in the spring. 



With the rapid multiplication above described it is not surpris- 



Fiq. 454. The apple-aphis, winged fall migrants on leaf natural size. 



ing that the foliage is soon covered with thousands of aphides, 

 and that with so many sucking the sap the leaves soon curl up 

 and drop. This is often a serious drain upon the vitality of 

 young trees, stunting their growth, and so weakening them that 

 they are more liable to be attacked by other insects and diseases, 

 while the premature dropping of the foliage prevents the full 

 growth of the tree and the proper hardening of the wood before 

 winter. This species shows marked preference for certain varieties 

 of apples and rarely injures others. Apple, pear and quince are 

 the only fruit trees infested by this species, which lives upon 

 them throughout the year. 



