JUMPING PLANT-LICE. 139 
Psyllidz are strictly vegetarian in their food habits. Most 
of them, like the plant-lice, feed upon the sap of plants, where 
they can cause serious damage if at all numerous; others form 
peculiar galls. 
To show the form of these peculiar beings two species are 
illustrated. 
Psylla pyricola Forster. (The Pear-tree Psylla). 
This jumping plant-louse has caused very severe losses upon 
pear growers in various parts of the Eastern States; in extreme 
cases it has destroyed extensive pear orchards by sucking the 
Fie. 130—Chrysopa species. After Brehm. 
sap from the smaller limbs and twigs, and in many other cases 
it seriously interferes with the successful cultivation of this fruit. 
As pears are not grown to any great extent in our state it is not 
necessary to describe the insect in detail, and it is sufficient to 
state that the adult and winged insect has a striking resemblance 
