ELM LEAE ROSETTE AND WOOLLY APHID OE APPLE. 339 



STRUCTURE KEY. 



Woolly Aphid of Apple. 



A. Apterous forms. Antennae without annulations. 



B. Females. 



C. Viviparous. 



D. Antenna typically 5-jointed, Fig. 68. Wax glands not 

 of type shown in Fig. 61. First spring generation 

 hatched from over-wintering egg and found in elm 

 rosette early in June Stem Mother. 



DD. Antenna 6 -jointed. Fig. 68, No. 80. Wax glands as 

 shown in Fig. 61 and Fig. 68, No. 80. Progeny of 

 stem mother developing in rosette in June 

 Second Elm Generation. 



DDD. Antenna 6-jointed. Fig. 68, No. 82. Wax glands of same 

 type as those shown in Fig. 61. On apple bark or 

 water shoots Summer Generations. 



DDDD. Structure about as with summer generations On apple 

 roots all times of year Root Generation. 1 !. 



DDD'D'D. 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 5-jointed, Fig. 64. 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. 65. 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-f-V-f-Vl. 

 VI typically without annulations. Fig. 68, No. 81. Developing 

 in June-July in elm rosette and migrating to apple, hawthorn 

 and mountain ash. Progenitor of summer generations 

 Spring Miaran t 



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

 typically with 2 or more annulations. Fig. 68, Nos. 83, 84, 85. 

 Developing in fall in woolly colonies on bark of apple, haw- 

 thorn and mountain ash. Fig. 62. Progenitor of true males 

 and females Fall Migrant 



