6 



HOW TO CONTROL THE PEAR THRIPS. 



middle of April the number on the trees diminishes rapidly, and by 

 the last of April all the larvae are off the trees and in the ground. 

 Here they work down into the first 3 or 4 inches of hard soil below 

 the loose surface mulch and construct a tiny cell, where they remain 

 until the following spring. 



Pupse. — The larvae mostly remain as such in these cells till Sep- 

 tember, when pupation begins, pupae (fig. 5) being most abundant 

 during October and November. Many adults can be found in the 

 ground in December, and by the 1st of January practically all the 

 thrips are in the adult stage and apparently ready to emerge and go 

 into the trees whenever conditions are right. Broadly speaking, the 

 thrips spend two months of the year in the adult, egg, and larval 



condition on the trees and the other 

 ten months of the year as larvae, 

 pupae, and adults in the ground. 



CONTROL MEASURES. 



The pear thrips is in some respects 

 an unusual insect in that it remains 

 in a dormant or semidormant condi- 

 tion for about ten months of the year. 

 Although on the trees for only two 

 months out of the twelve, it is able 

 in this short time, in the absence of 

 treatment, to completely destroy all 

 prospects of a crop of fruit, in many 

 cases within a very few days. The 

 trees are attacked at the period of 

 bud swelling and blossoming, when 

 they are most susceptible to injury. 

 These minute insects come literally 

 in swarms, and may, if left alone, 

 completely destroy all of the fruit 

 buds of an orchard in four or five days. Many cases have been 

 known where a delay of four or five days in spraying resulted in 

 loss of the entire crop of fruit, and in some cases half of all the 

 buds were killed in three days after the thrips appeared on the trees 

 in great numbers. In view of this condition it is very evident that 

 any means of control must be very thorough and done in the most 

 exacting manner at the proper time. 



EXPERIMENTS IN THRIPS CONTROL. 



Many experiments with soil fumigants, fertilizers, and irrigation 

 were made with the hope of killing the thrips while in the ground, 



Fig. 5.— The pear thrips: Pupa, greatly 

 enlarged. (Original.) 



