16 THE PEAR THRIPS. 



Sprayinf/.—lt has been stated with regard to killing thrips by means 

 of various spray mixtures that whatever these mixtures are they must 

 be thoroughly appHed to do even fair service. We have learned from 

 this year's experience that for this particular thrips spraying is a very 

 unsatisfactory means of control. The insect is hard to reach because 

 of its manner of hiding in bud or blossom, and difficult to kill without 

 injuring the tree with the spray mixture itself. Because of its haliits 

 of leaving the ground, extending over a period of several weeks, and its 

 habits of migrating, one might apply sprays and kill most of the insects 

 on his trees and within a very few days find an infestation as heavy as 

 before. The injury, as we have seen, is so rapid and so fatal, taking 

 but a few days (four or five) to ruin an entire orchard, that were we to 

 depend on sprays all work would necessarily have to be done in a com- 

 paratively short time and repeated often, and this of course is imprac- 

 ticable. 



It does not seem necessary at this time to give in detail the results 

 of the spraying experiments which we carried on during the past season. 

 Fourteen different formulas were tried, including various forms of soap 

 washes and caustics, tobacco, sulphur, crude carbolic and creosote oils. 

 The sprays were carefully prepared under the personal supervision of 

 Mr. Budlong and myself, and applied with a Bean power outfit with 

 the Bean Cyclone and Vermorel nozzles, under pressure of from 140 to 

 170 pounds. The results were very unsatisfactory. Exposed thrips 

 would be killed, but those within the blossoms or buds showed almost 

 no signs of injury. New adults and also young thrips, — for the young 

 continued emerging from the stems and leaves where the eggs had been 

 deposited, — appeared on the sprayed trees within a day or two after the 

 washes were applied, and after four or five days the trees revealed 

 almost as heavy an infestation of both young and mature thrips as 

 there was before any spraying had been done. No one wash proved 

 satisfactory, and apparently under the conditions none can. Sprays 

 will doubtless be tried again, but they can only lessen the number of 

 thrips with little or no appreciable results, and some injury to the tree 

 is almost certain to follow. 



Methods of Cultiration. — From the foregoing it might seem an almost 

 hopeless task to check the thrips by either natural or artificial means. 

 The insect, as we have seen, sj)ends the greater part of its life beneath 

 the soil, and this is probably tlie best time to attack it. After the larva 

 is fully grown, it leaves the food-plant and seeks a secluded place in 

 the ground. On entering the ground it follows openings such as cracks, 

 or holes made by other insects or worms, and reaching a depth of from 

 four to six inches, though often deeper, it hollows out a small cell on 

 the side of the larger opening, and thus securing itself awaits further 

 developments. 



