U.S. D. A., B. E. Bul. 68, Part I (Revised). D. F. I. I. September 20, 1909. 
PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
THE PEAR THRIPS. 
(Euthrips pyri Daniel.) 
By Duptry Moutron. 
Engaged in Deciduous Fruit Insect Investigations. 
INTRODUCTION. 
This paper brings together the results of an investigation of the 
life history, habits, natural enemies, and methods of control of the 
pear thrips (Huthrips pyri Daniel), a pest of deciduous fruit trees in the 
San Francisco Bay region of California. The investigation was under- 
taken at the request of the Santa Clara County 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 Valley, where the thrips seemed to be at its worst. The investi- - 
gation extended through a period of fifteen months, from February, 
1904, to April, 1905.4 
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. 
OCCURRENCE AND DISTRIBUTION. 
The pear thrips is known to exist in the 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 question 
whether the insect is a native of California or an introduced form. 
The pear thrips may have had some indigenous plant, such as the 
aThe writer wishes to acknowledge the work of Mr. Earl L. Morris and Mr. ©. T, 
Paine. He is indebted also to Prof. W. R. Dudley, head cf the department of sys- 
tematic botany, and to Dr. G. H. Pierce, of the Leland Stanford Junior University, 
for literature and helpful suggestions, and finally to Prof. Vernon L. Kellogg for his 
ever helpful suggestions and encouragement. 
