38 CIRCULAR 8 4 9, U. S. DEPT. OF AGRICULTURE 



Scoto gramma TRiFOLii (Rottemburg) 



Clover Cutworm 



Distribution. — This species is recorded throughout the United States, 

 Canada, Europe, and northern Asia. 



Economic status. — In the Great Plains States it is of minor economic 

 importance, 



Food plants and larval habits. — The larvae are diurnal and are 

 general feeders, but prefer beets and lambsquarters. On lambs- 

 quarters their coloration blends admirably with the grayish-green 

 foliage. On sugar beets the larvae prefer the older foliage, and often 

 strip the leaf to the petiole, leaving only the midrib. Small beet 

 plants are stripped of their foliage, but unless the crown is eaten they 

 usually recover. The writer has taken the larvae in small numbers 

 in alfalfa. 



Seasonal history. — Marsh (13) states that there are three generations 

 of this species each year in the Arkansas Valley in Kansas, and that 

 it passes the winter in the pupal stage in cells in the soil. During a 

 severe dust storm near Garden City, Kans., on March 21, 1935, the 

 writer found many exposed pupal cells along the edge of a field from 

 which the top soil had been blown away. Many cells had been broken 

 open, exposing the pupae, most of which were dead. Pupae in un- 

 broken cells lying on the soil surface were still living, and a number 

 that were brought into the laboratory yielded adults during the first 

 week in April. 



Adults were collected at light traps throughout the season from 

 March to November. At Garden City they were taken in greater 

 numbers than any other species of Phalaenidae; nearly 87,000 speci- 

 mens were recorded during the season of 1935 alone. Marsh (18) 

 states that the adults deposit eggs during the latter half of May, and 

 adults of this generation appear early in July. The larvae of the 

 third generation mature late in the fall, go into the winter in the 

 pupal stage, and produce adults the following spring. He also records 

 that the larvae are most numerous on beets during the latter half of 

 June, The writer found them most numerous on alfalfa and lambs- 

 quarters during September. 



Natural enemies. — Of 148 larvae collected in the field, 12 percent 

 were parasitized by Hymenoptera and 16 percent by Diptera and 22 

 percent died of disease. Parasites and disease organisms reared from 

 the larvae were as follows: 



Hymenoptera — Apanteles plathypenae Mues., Eulimneria sp. 



Diptera — Euphorocera sp. near tachinomoides (Tns.), Schizocerophaga sp., 



Zenillia hyphantriae (Tns.), Winthemia quadripnstulata (F.). 

 Disease organisms — Beauveria sp., unidentified wilt. 



Ceramica picta (Harris) 



Zebra Caterpillar 



Distribution. — This species is found in the Atlantic Coast States 

 and westward to Utah, as well as in the eastern Provinces of Canada. 



Economic status. — This caterpillar is of no economic importance in 

 the central Great Plains. Elsewhere, particularly in the eastern part 

 of its range, it is an important pest. 



