Western Army Cutworm Pale Western Cutworm 



When the nest was completed the wasp wandered about for several 

 minutes and finally went to the worm, grasped it by the throat and 

 carried it in almost a straight line to the mouth of the burrow, where 

 it was laid with its head toward the opening. She then entered the 

 burrow, turned around, came out, and grasping the worm, backed into 

 the burrow again, dragging it after her. After a few seconds, during 

 which time the egg was fastened to the worm, the wasp reappeared, 

 turned its head away from the mouth of the burrow, and, standing on 

 her four hind legs, clawed dirt into it with her front feet. Every little 

 while she turned around to ram the dirt into the opening with her head. 

 This was continued until the mouth of the burrow was completely filled. 

 The surface of the soil was left in such a condition that it was only with 

 the greatest difficulty that the writer could locate the burrow. 



The egg, shown fastened near the head of the worm in Figure 17, 

 Plate VI, Page 21, gradually changes into a maggot. The forward end 

 of this maggot, which contains the mouth, is long and pointed and during 

 the entire feeding period remains embedded in the body of the worm. 

 As the larva increases in size the worm shrinks until, when the grub is 

 fully grown, nothing but its empty skin remains, as shown in Figure 16, 

 Plate VI, Page 21. When the young wasp has exhausted its supply of 

 food its head is withdrawn from the empty skin of the worm. 



The next day or so is spent in lining its burrow with a silken cocoon, 

 within which the grub changes to the pupa and finally into the adult 

 wasp. 



Birds 



Birds are among the most effective natural checks of cutworms. 

 The meadow lark is probably one of the most valuable, its food in May 

 being about 24% caterpillars, the greater part of which are cutworms. 

 Blackbirds of all species, and robins, destroy large numbers of cutworms, 

 as do many other ground feeding species. 



(b) PALE WESTERN CUTWORM 



(Figs. 9, 10, 11 and 12, Plate I, Page 11) 



The pale western cutworm 12 is a western species which until 

 1911 was not known as seriously injurious. Reported outbreaks have 

 all occurred in the Great Plains and Rocky Mountain areas of the United 

 States and the prairies of Western Canada. 



Unlike the western army cutworm, this species does not occur in 

 alfalfa to any extent. Fall grain, crops planted on weedy fallow land 

 and those following grain are most apt to be injured. Seldom are crops 

 following cultivated crops injured unless they are adjacent to infested 

 fields. This is especially true of crops following sugar beets and potatoes. 



DESCRIPTION 

 The Worm 



The full grown worm (shown natural size, Fig. 9, Plate I, Page 11) 

 is a dirty, pale gray color. After eating its fill of green food it takes on 

 an olive tinge. The head and part of the first segment of the body back 

 of it are light brown. There are usually two dark lines on the head as 



( ,2 ) See explanation of "Reference Figures." page 2. 



45 



