FAMILY PSYLLIUM 



115 



Apple Leafhopper (Empoasca mali). — The apple leafhopper, 

 another very destructive form, affects apple and other 

 fruit trees. Occasionally it is destructive to alfalfa, cow 

 peas, potatoes and beans. 



Fiu. 



1. — Pear-tree psylla: adult female — natural size indicated by side 

 line. (From Marlatt, Div. Ent., U. S. Dept. Ag.) 



The Sternorhynchi include those Homoptera that have 

 the beak fused into the sternum. The group contains some 

 remarkably specialized forms of insects and there are four 

 distinct families, closely linked together by connecting 

 forms. 



Psyllidae. — The Psyllidce seem closely related to the 

 cicadas. The shape of the body and head is like that in the 



