34O MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



HABITAT KEY. 



WOOLLY APHIDS OF THE ELM. 



A key 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 Ulmus americana. 

 Throughout the summer on young elms. No alternate host 

 known. Widely distributed in America S. rileyi. 



AA. Spring generations in elm leaves, causing various types of 

 deformation. 



B. Large baggy gall on Ulmus campestris. Alternate host un- 

 known. European species. Taken in Connecticut in 1913 

 5. lanuginosa. 



BB. Terminal leaf cluster or rosette (Figs. 59~6o) on Ulmus ameri- 

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

 thorn. Maine to Colorado 



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



BBB. Leaf curl or roll type of deformation. 



C. 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). 



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

 eration with wax gland distinctly unlike those of Fig. 

 61. Spring migrant with antenna typically with III not 

 longer than IV+V+VI. Alternate host Amelandner 

 the roots of which are infested.* Maine to California 

 S. americana in part, of authors. 



*Bulletin 241. Maine Agricultural Experiment Station. 



