U.S. D.A., B. E. Bul. 80, Part IV. D. F. I. 1., September 1, 1909. 
PAPERS ON DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
THE PEAR THRIPS AND ITS CONTROL.? 
(Euthrips pyri Daniel.) 
By Duprey Moutton, 
Engaged in Deciduous Fruit Insect Investigations. 
INTRODUCTION. 
Cultivation and spraying, the principal treatments involved in the 
control of the pear thrips, are largely subject to suitable weather con- 
ditions, and each, to be effective, must be accomplished at its proper 
time. Other orchard work, such as irrigation, cultivation, pruning, 
and spraying for other insect and fungous troubles, must therefore be 
considered well beforehand and completed or so arranged that nothing 
will interfere with the treatment for the thrips. It is highly impor- 
tant that the individual orchardist should have everything in readiness 
to treat his own orchard at exactly the right time. Preparedness for 
and thoroughness in the work of spraying and in plowing, it will be 
found, are the most important factors in the successful control of this 
insect. 
DISTRIBUTION. 
The pear thrips is known to occur only in the central part of Cali- 
fornia, and especially in localities in the general neighborhood of the 
San Francisco Bay. Reports of its ravages have been received from 
the Sierra Nevada foothills, near Newcastle and Auburn, and from the 
@The control of the pear thrips has been for several years the principal problem 
confronting the growers of deciduous fruits in portions of central California. This 
insect, on account of its mode of attack and habits, has presented unusual difficulties 
in control. It is believed, however, that the investigations of the Bureau of Ento- 
mology have now determined practical and efficient measures which, if carefully 
followed out by orchardists, will insure its reduction below injurious numbers. The 
investigation has involved a large amount of detailed study of the insects’ behavior 
on the trees and in the ground, and the testing of a large series of spray mixtures, fer- 
tilizers, soil fumigants, etc. Mr. Moulton has been continuously engaged in the work 
for the past three years, assisted a part of the time by Messrs. Charles T. Paine and P. R. 
Jones. Beginning with the spring of 1909, Mr. S. W. Foster was charged with the 
operations in Contra Costa County and northward, Mr. Fred Johnson collaborating dur- 
ing the spring months. The presentis the second report upon the pear thrips, the first, 
published as Part I of Bulletin 68 of this Bureau, dealing largely with the insect’s life 
history and habits..—A. L. QUAINTANCE. 
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