Alfalfa Webworm 



the dark stripe and one on the lower. Just below the dark stripe is an- 

 other light, more or less flesh-colored one, and below this the body is 

 dusky, but not so dark as the other dark portions. There are several 

 dark circles within the dusky portion, each bearing a bristle. The lateral 

 portions of the first segment back of the head are dark. The head is 

 mottled with dark brown on a lighter ground color. 



The worms are very active. If their webbed retreats on alfalfa are dis- 

 turbed they throw themselves to the ground or run rapidly down the 

 stems. 



When on sugar beets they will be found concealed at the end of the 

 long, silken tube already mentioned, among the clods near the crown of 

 the plant. If the soil is disturbed the worms run rapidly to the web 

 among the leaves, and if disturbed here they descend to the end of the 

 tube again just as rapidly. They appear to travel backward as freely as 

 forward. 



The Pupa 



When fully grown the worms enter the soil and spin a cocoon very 

 similar to that of the sugar beet webworm, but more loosely made, in 

 which they change to the pupa (Fig. 2, Plate VI, Page 21). The pupa is 

 very much like that of the beet webworm, but can be readily distinguished 

 from it by the eight spatulate (spoon-shaped) appendages at the tip (Fig. 



3, Plate VI, Page 21), those of the sugar beet webworm being curved and 

 pointed. 



The Moth 



In warm weather the moths appear in about six or eight days after 

 the worms change to pupae. By comparing the figure of this moth (Fig. 



4, Plate VI, Page 21) with that of the sugar beet webworm (Fig. 11, 

 Plate V, Page 19), the differences are clearly brought out. It will be 

 noticed that the under wings of the alfalfa webworm are much darker 

 than those of the sugar beet webworm moth and that the markings of the 

 upper or fore wings are darker as well as different in form. Flying in the 

 field the two are very hard to distinguish from each other. 



LIFE HISTORY 



So far as known to the writer, there are no published accounts of the 

 life history of this insect. In general it is probably quite similar to that 

 of the sugar beet webworm. The injury to alfalfa referred to above 

 occurred during the last of June. The moths of this brood appeared July 

 14th. During August another brood of worms appeared. This second 

 brood was not so numerous and did less damage than the first. In all 

 probability, in the latitude of Denver, the winter is passed in the larval 

 or pupal stage. 



NATURAL ENEMIES 



An undescribed Tachina-fly, 15 (Fig. 11, Plate VI, Page 21), was 

 reared from caged worms. 



Birds and poultry no doubt do much to hold this insect in check. 



( 1B ) See explanation of "RePerence Figures," page 2. 



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