DESTRUCTIVE INSECTS. 181 



247) are active creatures, quickly jumping and flying out of 

 reach when approached ; they feed, but not enough to do no- 

 ticeable damage. 



The insect hibernates in the adult stage, hidden in the crev- 

 ices under the loosened bark on the trunk and large limbs of 

 the pear trees. During warm days they often crawl about on 

 the branches and trunk. They are not easily seen as they are 

 so small, and their color so closely imitates the bark. In 



FIG. 247. FIG. 248. 



The Pear Psylla. Adult and nymph, much enlarged. 



April these adults lay their curious, orange-yellow eggs in the 

 creases of the bark about the bases of the terminal buds of the 

 preceding year's growth. By the middle of May, or about the 

 time the first leaves are expanding, most of the eggs have 

 hatched, and the little nymphs are at work sucking out the 

 life of the tree. In about a month these nymphs have devel- 

 oped into adult psyllas, which are smaller than those which 

 hibernated, and they soon lay eggs on the leaves for another 

 brood. At least four broods of the insect develop in a season 

 in New York and probably five in Maryland. Many pear-trees 

 are so much weakened by the drain of so many little pumps 

 sucking the sap that they do not have enough vitality to sur- 

 vive the winter. The insect is thus both a serious menace to 

 the tree and to the crop of fruit. 



It is very important that this pest should be checked early 

 in the season, as the psyllas can be more easily hit with a 



