WOOLLY APHID OF THE APPLE. 183 



STRUCTURE KEY. 



Woolly Aphid of Apple. 



A. Apterous forms. Antennae without annulations. 



B. Females. 



C. Viviparous. 



D. Antenna typically S-jointed, Fig. 79. Wax glands not of type 

 shown in Fig. 72. First spring generation hatched from 

 over-wintering egg and found in elm rosette early in 

 June Stem Mother. 



DD. Antenna 6- jointed. Fig. 80. Wax glands as shown in Figs. 

 72 and 80. Progeny of stem mother developing in rosette 

 in June Second Elm Generation. 



DDD. Antenna 6- jointed. Fig. 82. Wax glands of same type as 

 those shown in Fig. 72. On apple bark or water shoots 

 Summer Generations. 



DDDD. Structure about as with summer generations. On apple 

 roots all times of year Root Generations. 



DDDDD. Young born late in fall and living over winter about 

 crown of tree, apparently without feeding until 

 spring, when they ascend to apple bark and attain 

 their growth Hibernating Nymphs. 



CC. Oviparous. 



Antenna S-jointed, Fig. 75. Minute beakless form which 

 deposits the over-wintering egg. Rarely seen but easily 

 obtained by imprisoning fall migrant in vial. .True Female. 



BB. Minute beakless form smaller and more slender than true 

 female. Antenna 5- jointed. Fig. 76. Rarely seen but easily 

 obtained by imprisoning fall migrant in vial True Male. 



AA. Alate forms. Antennae with annulations. 



B. Antenna typically with III as long as or longer than IV-(-V-|-VI. 

 VI typically without annulations. Fig. 81. Developing in June- 

 July in elm rosette and migrating to apple, hawthorn and 



mountain ash. Progenitor of summer generations 



Spring Migrant. 



BB. Antenna much as in spring migrant, though usually shorter. VI 

 typically with 2 or more annulations. Figs. 83, 84, 85. Devel- 

 oping in fall in woolly colonies on bark of apple, hawthorn 

 and mountain ash. Fig. 73. Progenitor of true males and 

 females Fall Migrant 



