INSECTS INJURIOUS TO THE APPLE AND PEAR 



531 



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

 tinguished after the third molt by the blackish wing-pads at 

 the sides of the body. With the first frost 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 



FIG. 460. The apple-aphis; a, young tree partially defoliated by the aphis; 

 d, winter eggs on twig. 



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

 the places mentioned. All of the aphids 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- 

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

 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 



