Pale Western Cutworm 



shown in the figure. The small dark spots on the segments of the abdo- 

 men, each bearing a short stiff bristle, are usually plainly visible. 



Just beneath the skin of the back is an organ which fulfills the 

 offices of the heart in the higher animals. This shows as a dark line 

 in the center of the back running nearly the whole length of the worm. 

 If watched closely it will be seen to pulsate in true heart fashion when 

 the worm is alive. 



The Pupa 



The pupa resembles that of the western army cutworm so closely 

 that Figure 2, Plate I, Page 1 1, will suffice for both. Aside from some 

 minor structural differences the only difference is in the size. The pupa 

 of the species under consideration is slightly smaller than that of the 

 western army cutworm. 



The Moth 



Figure 10, Plate I, Page 11 represents the moth, natural size. The 

 whole insect is lighter than the moth of the western army cutworm. 

 The colors are chiefly delicate shades of tan and brown. These moths 

 fly more freely during the day than those of the preceding species. On 

 warm afternoons in fall they have been seen feeding on the blossoms of 

 "rabbit brush" in quite large numbers. 



LIFE HISTORY 



The life history of the pale western cutworm is essentially the same 

 as that of the western army cutworm. The only important differences 

 are in the dates when feeding ceases and the changes from worm to pupa 

 and pupa to moth take place. For a description of how and where these 

 changes take place read those parts of the discussion of the western 

 army cutworm under the heads "The Pupa" and "The Moth' "(Page 41). 



This cutworm is single brooded in Northern Colorado. The eggs, 

 shown very much enlarged in Figures 11 and 12, Plate I, Page 11, are a 

 little less than s \ of an inch in diameter. The eggs are laid during 

 September and October, and so far as known are deposited either in 

 cracks in the soil, on lumps of soil or on the surface of the soil. Seldom, 

 if ever, are they deposited on green plants. Dry, fallow land and stubble 

 fields are ideal locations for egg laying. 



During open, warm falls some eggs may hatch before winter sets in, 

 but field observations indicate that the greater part of the eggs do not 

 hatch until spring. As soon as hatched the worms begin feeding and 

 continue to feed until the last of June or the first or second week of July. 

 Because of this late feeding habit late planting cannot be re- 

 sorted to as a means of preventing loss, as no profitable field 

 crop can be planted at this late date. 



The worms remain in their earthen cells for two or three weeks 

 before the change to the pupa takes place. In about four weeks more 

 the moth emerges. 



NATURAL ENEMIES 



Little is known of the natural enemies of the pale western cutworm. 

 In all probability it is held in check by some of the same parasitic and 

 predacious insects and birds as the western army cutworm. 



46 



