REPORT OF THE DEPARTMENT OF 

 ENTOMOLOGY. 



THE PEAR THRIPS.* 



p. J. PARROTT. 



SUMMARY. 



For several years pear blossoms in orchards in the Hudson 

 River Valley have blighted, resulting in more or less extensive 

 losses in fruit yields. Studies during the past spring have shown 

 that the injury is caused by the pear thrips (Euthrips pyri 

 Daniel), a new orchard pest, which has attracted considerable 

 attention in recent years in California because of its destructive- 

 ness to various deciduous fruits. 



The adult thrips, which is largely responsible for the injuries 

 to the trees, is a small^ darkish brown, winged insect measuring 

 about one-twentieth of an inch in length. It appears in de- 

 structive numbers when the buds are opening, attacking the 

 tenderest of the flower parts. The eggs are mostly deposited 

 beneath the epidermis of the blossom and fruit stems. Hatch- 

 ing takes place within a few days, and the larvae seek preferably 

 the calyx cups, undersides of calyces, and the folds or under 

 surfaces of the tender, expanding leaves. The larvae feed for 

 about two weeks and drop to the ground, in which they form a 

 protecting cell. In this cell the insect completes its transforma- 

 tions and emerges from the ground in the spring as an adult. 

 The thrips is single brooded; and the most active and destruc- 

 tive stages are coincident with the period that includes the life 

 events of the swelling and opening of the buds and dropping of 

 blossoms and calyces. 



Injuries by the thrips in the Hudson Valley have apparently 

 occurred over a period of five years. During the past three 

 years fruitgrowers generally have noticed blighting of blossom 

 clusters of pear trees, although the nature of the causal agent 



*A reprint of Bulletin Xo. 343, January, 1912; for "Popular Edition," 

 see p. 809, 



[341] 



