U. S. 1). A., B. E. liul. r,s, I'arl I. D. F. I. I. June lU, l!>n; 



PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



THE PEAR THRIPS. 



(Eiilhrips jii/ri. Daniol.) 



T?y DiDi.F.v Moii/roN. 



Engnfjcd i)i Drnduoii.s Fniii Insect liirislii/alions. 



INTRODUCTION. 



This paper l)rings together the resuks of an investigation of the 

 hfe history, hahits, natural enemies, and methods of control of the 

 pear thrips {Fluthrips pyri Daniel), a pest of deciduous fruit trees in tlie 

 San Francisco Bay region of California. The investigation was under- 

 taken at the re({uest of the Santa Clara Comity board of supervisors, 

 who furnished the funds and liberally granted necessary facilities 

 for a thorough and scientific study, and was carried out in the Santa 

 Clara ^^^lley, where the thrips seemed to be at its worst. The investi- 

 gation extended through a period of fifteen months, from February, 

 1904, to April, 1905.« 



The writer offers this paper rather as an introduction for future work 

 than as a completed account, and it is intended especially for the fruit 

 grower, that he may understand the nature of the insect and its injury. 

 The alarm felt for the safety of the deciduous fruit industry, which 

 the pear thrips caused during 1904 and 1905, in the light of our pres- 

 ent knowledge need not again be experienced, and, although no effect- 

 ive means of control are yet offered, a knowledge of the life habits 

 should do much to clear away the uncertainty usually following the 

 first appearance of a destructive pest in any locality. 



OCCUmiENCE AND DISTRIBUTION. 



The pear thrips is Jviiown to exist in tlie San Francisco Bay counties 

 and along the Sierra Nevada foothills, but it is not known how widely 

 the pest is distributed outside of these localities. It is still a cjuestion 

 whether the insect is a native of California or an introduced form. 

 The pe r thrips may have had some indigenous plant, such as the 



o The writer wishes to acknowledge the work of Mr. Earl L. Morris and Mr. C. T. 

 Paine. Ht- is indelitod also to Prof. W. R. Dudley, head of (he department of systeniat ic 

 botany, and to Dr. G. H. Pierce, of the Leland Stanford Junior I^niversity, for literature 

 and helpful suggestions in carrying on the work on the fungus which appears to be one 

 of the natural checks for EiUhnps pyri, and finally to Prof. Vernon L. Kellogg for his 

 ever helpful suggestions and encouragement. 



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