Cutivorms Western Army Cutworm 



Late Planting 



Late planting may sometimes be resorted to as a means of prevent- 

 ing loss by cutworms. However, before resorting to this means the 

 best plan, if one is in doubt as to the identity of the particular cutworm 

 in question, is to send some of the worms to the State Entomologist, 

 to the Experimental Department of The Great Western Sugar Company, 

 Longmont, Colorado, or to some one else familiar with these insects and 

 qualified to give advice regarding them. If this is done much time and 

 many dollars may be saved. Before resorting to late planting read 

 carefully what follows about the different species of cutworm, especially 

 the Pale Western Cutworm. 



(a) WESTERN ARMY CUTWORM 

 (Figs. 1, 2, 3 and 4, Plate I, Page 11) 



The name "western army cutworm" has been applied to this species 

 because under favorable conditions it becomes very numerous and at 

 such times travels en masse in much the same way as the true army worms. 



It is also often called the "alfalfa cutworm," because of its prefer- 

 ence for this crop. In Northern Colorado it seldom injures crops unless 

 they are planted on recently broken alfalfa land or in fields adjoining 

 infested alfalfa fields. 



DESCRIPTION 

 The Worm 



Figure 1, Plate I, Page 11 represents a full grown western army 

 cutworm, natural size. This worm is marked with various shades of 

 brown above, while the lower part is a dirty white. There are usually 

 several dark spots on each segment of the body. Each of these bears 

 a short, stiff bristle. These bristles are not always easily seen with the 

 naked eye. Some individuals are much darker than in the figure, while 

 others are lighter. This is the most common cutworm in alfalfa fields. 



The Pupa 



Shortly after the cutworm becomes full grown it burrows into the 

 soil to a depth of about two inches. The next few days are spent in 

 wriggling and twisting about, making a cosy cell in the soil. 



Rapid changes now begin to take place in the worm. It gradually 

 shortens and changes from its original color to a dirty, whitish yellow. 

 The skin, which has become much shrunken and wrinkled, now cracks 

 open, exposing a yellowish brown object within. A few more twists 

 and turns and the pupa (Fig. 2, Plate I, Page 11) frees itself from the 

 skin which covered the worm. 



The Moth 



The change from worm to pupa is only the beginning. During the 

 next two or three weeks nature is at work within the brown walls of 

 the pupa forming a body, legs and wings and hundreds of feather-like 

 scales (Fig. 4, Page 42) to cover them. When all is complete, our ugly 

 cutworm has taken on still another form. The brown walls of the pupa 

 burst open and after much pulling and straining the moth emerges. 

 At each side of its body hang two crumpled objects. As we watch these 

 they begin to expand and lengthen. In a very short time they have 



41 



