UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 421 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



October 26, 1916 



THE SUGAR-BEET THRIPS. 



By Wm. H. White, Scientific Assistant, Truck Crop and Stored Product Insect 



Investigations. 



CONTENTS. 



Introduction 1 



General description 1 



History 2 



Distribution 2 



Food plants 2 



Extent and nature of injury 3 



Habits of nymphs of first and second stages . 3 



Habits of n3-mplis of third and fourth stages. 4 



Habits of the adult . 



Descriptive 



The egg 



The nymph 



The adult 



Life cycle 



Control 



Bibliography 



INTRODUCTION. 



During the winter of 1916 the sugar-beet thrips (Heliothrips femor- 

 alis Renter) was found in large numbers in a greenhouse at Washing- 

 ton, D. C. While attacking a variety of plants, the insect confined 

 itself principally to sugar-beet seedlings. Although long recognized as 

 a greenhouse pest, the sugar-beet thrips occurs out of doors in some 

 locahties and is recorded as having a large number of food plants. 

 Short notes on its injurious habits have been recorded and published 

 from time to time, but as far as known the life history and habits of 

 the immature stages hitherto have not been fully determined. 



GENERAL DESCRIPTION. 



In color this species is dark brown or black, the head, prothorax, 

 and the end of the abdomen being reddish yellow. The eyes are 

 dark brown. The forelegs are yellow, the middle and posterior pair 

 yellow with bn)wn femora or thighs. The wings are dusky, the 

 posterior pair hghtcr, crossed by a white band at the base and a white 

 band about two- thirds the distance from the base; the tips are 

 white. The antenna? are three times as long as the head. The total 

 length is about 1 .3 millimeters. 



> The writer wishes to express his apprecfatlon to Dr. F. H. Chittenden, under whose direction this 

 work wasconducte'l, for many helpful suggestions, and to Mr. J. D. Ifood, forf urnishing many references 

 to literature fjertairiing to this subject. 

 5.>47a°-Bull. 421-10 1 



