New Yoi^k AGRrcuLTUEAT. Experiment Station. 363 



a crop may be ruined in a few days through the destruction of 

 rudimentary blossom parts, and because of the repeated spraying 

 and thoroughness of treatments required to destroy the thrips con- 

 cealed in the partly opened buds. 



In this season's work at Germantown two factors greatly fav- 

 ored the experimental operations : the relatively small size of the 

 pear orchards in the community, which permitted thorough spray- 

 ing of entire orchards by power outfits on successive days, and 

 the rapid development of the buds owing to unseasonable hot 

 weather during the latter part of April which made the thrips 

 more exposed to treatment than if the growth of the buds had been 

 less rapid. 



Under the conditions which prevailed this year spraying proved 

 very efficient, and no treatment was made which did not effect a 

 considerable reduction of the numbers of thrips in the different 

 plats. Two or three sprayings on successive days reduced the 

 adult thrips to a very small percentage of those that were origi- 

 nally present on the trees. The larvae on pears proved especially 

 susceptible to treatment, and in the Hover orchard very few 

 escaped, which should greatly simplify future operations in this 

 planting for this pest. 



In view of the history of the thrips it is not desirable to draw 

 conclusions on a single season's experiments as the problem may 

 take on new aspects under different seasonal conditions. It is the 

 intention of the Station to continue its investigations on the thrips 

 until efficient methods of control have been satisfactorily demon- 

 strated. The purpose of this bulletin has been largely to encour- 

 age spraying as the most promising remedy for the present, and 

 to make more available locally the knowledge that exists on a new 

 and important fruit pest. 



