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



successfully in the Great Plains region. Adults were never numerous, 

 and only one larva was collected. Adults were taken at lights during 

 July and August. 



Life cycle. — At Wichita, Kans., eggs deposited on August 24 

 hatched in 5 days. They were 0.58 to 0.61 mm. in diameter and 0.42 

 to 0.53 mm. in height. The periods required in the various stages 

 and the width of the head capsule in the different larval ins tars were 

 as follows: 



Stage: period Width of head 



Instar: (days) capsule (mm.) 



First 3 to 4 0.35 to 0.40 



Second 2 to 3 .55 to .70 



Third 2 to 5 .85 to 1.10 



Fourth 2 to 5 1.40 to 1.60 



Fifth 2 to 8 1.80 to 2.35 



Sixth 6 to 11 



Total 19 to 24 



Pupa 24 to 38 



Egg to adult 48 to 64 



Beproductive capacity. — Two females taken at bait, when dissected, 

 contained 862 and 722 eggs. 



Peridroma margaritosa (Haworth) 



Variegated Cutworm 

 (Figs. 4, S; 5, C; 7, M) 



Distribution. — Crumb (5) states that this species occurs in the 

 Americas from Alaska to Patagonia and in Europe and the Mediter- 

 ranean region generally. 



Economic status. — It is of major economic importance over much of 

 the United States, and in the central Great Plains it is at times very 

 destructive in alfalfa and sweetclover. 



Food plants and larval habits. — The list of food plants is extensive. 

 When the larvae occur in great numbers, they assume the army 

 habit. This species is not entirely nocturnal, and frequently feeds 

 in the daytime, especially on cloudy or partly cloudy days. In their 

 younger stages the larvae rest on the plants, but the larger larvae 

 have a tendency to hide during the day. 



Seasonal histo?*y. — In Kansas the adults have been taken every 

 month except December, January, and February. Because all stages 

 may be found in the field in May and June, it is difficult to determine 

 from field observations the number of generations a year. Crumb (5) 

 states that there are four in Tennessee. The writer has reared three 

 and a partial fourth generation in one year at Manhattan, Kans. In 

 the central Great Plains the important generation is the one that is 

 in the larval stage during May and June, because the others are re- 

 duced to small numbers by repressive factors. During the summer 

 the adults are scarce, but the number increases gradually until cold 

 weather comes in the fall. All attempts to carry the larvae through 

 the winter, either in outdoor cages or in the laboratory, have failed. 

 The pupa appears to be the usual overwintering stage, but survival 

 is low even during normal winters. The relatively few survivors are 

 able to carry the species to high population levels, owing to their 

 enormous reproductive capacity. 



