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. 
Page. 
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 nymphs 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 (Heliotlirips femor- 
alis Reuter) was found in large numbers in a greenhouse at Washing- 
ton, D. G. 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 
localities 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 brown femora or thighs. The wings are dusky, the 
posterior pair lighter, 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 antennae are three times as long as the head. The total 
length is about 1.3 millimeters. 
i The writer wishes to express his appreciation to Dr. F. H. Chittenden, under whose direction this 
work was conducted, for many helpful suggestions, and to Mr. J, D. Hood, for furnishing many references 
to literature pertaining to this subject. 
55479°— Bull. 421—16 1 
