184 MAINE AGRICUI,TURAI, EXPERIMENT STATION. I913. 



HABITAT KEY. 



Woolly Aphids of the Elm. 



Those species not migrating to apple are to be treated in a separate 

 bulletin but a key is given here to aid in distinguishing the woolly aphid 

 of the apple from the other elm species with which it may easily be 

 confused in the spring of the year. 



A. Conspicuous woolly colonies on bark of Uhmis americana. 

 Throughout the summer on young elms. No alternate host 

 known. Widely distributed in America 5". rileyi. 



AA. Spring generations in elm leaves, causing various types oi de- 

 formation. 



B. Large baggy gall on Ulmiis campestris. Alternate host unknown. 

 European species. Taken in Connecticut in 1913..5'. lanuginosa. 



BB. Terminal leaf cluster or rosette (Figs. 70-71 on Ulmus ameri- 

 cana. Spring migration to apple, mountain ash, and haw- 

 hawthorn. Maine to Colorado : 



S. lanigera {americana in part, of authors). 



BBB. Leaf curl or roll type of deformation. 



C. Leaf roll as shown in Fig. 67. Wax glands of apterous genera- 

 tions and antennae of winged generations apparently the 

 same as those of the rosette dweller. Spring migration to 



apple. Recorded as yet only from the south 



5. lanigera {americana in part, of authors). 



CC. Leaf roll of Ulmus scabra and U. campestris. Antenna of 

 winged generations with V and VI without annulations. 

 Spring migration to gooseberry and currant. European 

 species. In America found in California, Oregon and 

 Maine (1913) S. ulmi {fodiens). 



OCC. Leaf roll of Ulmus americana. Second apterous spring gen- 

 eration with wax gland distinctly unlike those of Fig. 72. 

 Spring migrant with antenna typically with III not 

 longer than IV-|- V-f- VI. Alternate host unknown. Maine 

 to California S. americana in part, of authors. 



