. Bulletin of the Department of Agriculture. Agriculture. BULLETIN No. 421 '^^ _ „, . -^i*-; 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 tnird and fourth stages. 4 Habits of the adult. Descriptive The egg The nymph Th
. Bulletin of the Department of Agriculture. Agriculture. BULLETIN No. 421 '^^ _ „, . -^i*-; 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 tnird 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 Reuter) 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 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 determmed. GENERAL DESCRIPTION. In color this species is dark brown or black, the head, prothorax, and the end of the abdomen bemg 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. Tlie total length is about millimeters. 1 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, forfurnishing many references to literature pe
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