LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Entomology, 

 Washington, B.C., December 13, 1910. 



Sir: I have the honor to transmit herewith the manuscript of a 

 bulletin to be entitled ''Synopsis, Catalogue, and Bibliography of 

 North American Thysanoptera, with Descriptions of New Species." 



During the past few years the order Thysanoptera in America has 

 been the subject of increased study by entomologists, not only on 

 account of the extreme interest attaching to the insects themselves, 

 but also by reason of the considerable importance which several of 

 the species have attained as pests of horticultural and other crops. 

 Mr. Moulton, while in the employ of this bureau, was a part of the 

 time engaged in a study of two very destructive species in California, 

 namely, the pear thrips (Euthrips pyri Daniel) and the orange thrips 

 (Euthrips citri Moulton), and the present paper is an outgrowth of 

 data and specimens collected during his investigation of these insects 

 for the bureau. 



An up-to-date synopsis and catalogue of the Thysanoptera is 

 greatly to be desired and will be of much use to students of this order. 

 I would therefore recommend the publication of this paper as Tech- 

 nical Series No. 21 of the Bureau of Entomology. 

 Respectfully, 



L. O. Howard, 

 Chief of Bureau. 

 Hon. James Wilson, 



Secretary of Agriculture. 



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