PEAli AND QUINCE INSECTS 223 



The Pear Thrips 

 Euthrips yyri Daniel 



In the San Francisco Bay region of California, since 1904, 

 pears, prunes, apricots, peaches and ahnonds have suffered 

 greatly from the attacks of this minute, fringe-winged insect. 

 More recently this pest has appeared in injurious numbers both 

 in New York state and in England. The dark brown adults, only 

 about 2V ii^^^li ill length, emerge from the ground and attack 

 the bursting buds of the fruit trees in late February and early 

 March in California. They work their way into the opening 

 buds and feed on the tenderest parts of the unopened leaves 

 and blossoms. In feeding they pierce and rasp away the epider- 

 mis with their mouth parts and then suck out the sap. The 

 female inserts her minute, whitish, bean-shaped eggs principally 

 in the stems of the young fruit and leaves. The eggs hatch 

 in about four days. The young nymphs are white with red 

 eyes, closely resembling the adults in form, except for the lack 

 of wings, and have similar feeding habits. They attain their 

 growth in two or three weeks and fall to the ground, where, at 

 a depth of several inches, they form a small earthen cell within 

 which they hibernate. Most of the cells are found in the first 

 3 or 4 inches of firm soil ; none are made in the loose surface 

 layer. During the winter months the nymphs change to adults 

 within the cells, but the latter do not emerge till the last of 

 February in California. 



The injury is greater on those fruits which, like the pear 

 and prune, bear the blossoms in clusters all developed from 

 one bud, than on the peach and apricot, where only one blossom 

 comes from a single bud, because in the former case the thrips 

 have more chance to work before the fruit sets. Pears and prunes 

 suffer most severely. When abundant a large number of thrips 

 will enter a single bud, stunt the leaves, blast the blossoms and 

 prevent the setting of the fruit. On pears most of th(^ injury 



