U. S. D. A.. B. E. Bill. ]27, Tart II. T. C. & S. P. I. I., May 19, 1913. 



PAPEES ON INSECTS AFFECTING VEGETABLE AND 



TEUCK CEOPS. 



THE STRIPED BEET CATERPILLAR. 



(Mamestra trifo^ll Rott.) 



By H. O. Marsh, 

 Entomological Assistant. 



INTRODUCTION. 



Among the caterpillars or " ^Yorms " which infest sugar beets 

 in the Arkansas Valley in Colorado and Kansas is the so-called 

 garden Mamestra or clover cutworm {Mamestra trifolii Rott.). This 

 insect is ordinarily one of the minor beet pests, although during some 

 3'ears it develops in sufficient numbers to cause noticeable damage. 

 The writer had this insect under observation in the Arkansas Valley 

 during portions of four years (1909-1912), and this article is based 

 on notes made during those years. 



In the Arkansas Valley the larvre were found on two plants only — 

 sugar beet and lamb's-quarters {Chenopoduim- alhinrv). Sugar beet 

 appeared to be the favorite. 



EXTENT OF INJURY. 



Except in the year 1011 the larvae were rare and caused practically 

 no damage throughout the years the species was under observation. 

 During 1911 hundreds of beet fields were examined in the territory 

 between Pueblo, Colo., and Garden City, Kans., and almost without 

 exception the larvae were found on beets in all of these fields. The 

 larva" were most abundant and generally distributed during the 

 middle and latter half of June. During this month about 75 acres 

 of small beets in various portions of the valley were obser^^ed to be 

 stripjDed of foliage. About 5 acres were destroyed. As a rule tlie 

 defoliated beets promptl}^ recovered and put out new leaves, but 

 occasionally the larvae destroyed the crowns of the plants, and wlien 

 this damage occurred the plants died. 



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