U. S. D. A.. B. E. Bui. 127, Part II. T. C. & S. P. I. I., May 19, 1913. 
PAPERS ON INSECTS AFFECTING VEGETABLE AND 
TRUCK CROPS. 
THE STRIPED BEET CATERPILLAR. 
(Mamestra trifolii Rott.) 
By H. O. Marsh. 
Entomological Assistant. 
INTRODUCTION. 
Among the caterpillars or " worms " 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 
years 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 larva? were found on two plants only- 
sugar beet and lamb's-quarters (Chenopodium. album). Sugar beet 
appeared to be the favorite. 
EX-TENT OF INJURY. 
Except in the year 1911 the larva? 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 larva? 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 observed to be 
stripped of foliage. About 5 acres were destroyed. As a rule the 
defoliated beets promptly recovered and put out new leaves, but 
occasionally the larva? destroyed the crowns of the plants, and wlien 
this damage occurred the plants died. 
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