Sugar Beet Webworm 



occur in groups of from two to five or six or even more, when they are 

 placed in rows, the eggs overlapping as shown at "B" and "C." 



The Worm 



Figure 3, "A," Plate V, Page 19 shows a young webworm, natural 

 size, on a beet leaf. Figure 4, Plate V, Page 19 shows this same worm 

 much enlarged. As they grow larger these worms become darker, 

 appearing more like the full grown worms. 



The full grown worm is shown enlarged in Figure 6, Plate V, Page 

 19. They are not very variable in color, although some individuals 

 are somewhat lighter than the figure. The most characteristic marking 

 is the dark line in the center of the back with the row of dark circles on 

 either side, each with a small bristle in the center. These circles are 

 grouped in pairs. When disturbed the worms jerk their bodies violently 

 from side to side, often throwing themselves from the leaf. 



The Pupa and Cocoon 



The cocoon (Fig. 8, Plate V, Page 19) is composed of silk which is 

 produced by the worm. These silken tubes, which are often 1| to 2 

 inches long, reach to the surface of the soil. When removed with the 

 earth adhering to them they appear like small earthen rods. The light 

 portion of the figure shows where the soil has been scraped away, re- 

 vealing the cocoon beneath. 



The pupa (Fig. 9, Plate V, Page 19) is very active. When disturbed 

 it will twist and squirm about in very much the same manner as the worm. 

 At the tip are eight curved spines, four on either side, as shown in Figure 

 10, Plate V, Page 19. 



The Moth 



The moth (shown natural size, Fig. 11, Plate V, Page 19), with 

 its delicate shades of gray, brown and tan, harmonizes so well with the 

 colors of the soil that when resting on the ground it is hard to distinguish 

 from its surroundings. When at rest its wings are folded over the body 

 so that the moth is triangular in form like the outline drawing to the left 

 of Figure 4, Plate VI, Page 21 . When disturbed the moths fly up, mak- 

 ing short, jerky, zigzagging flights. 



LIFE HISTORY 



The first webworm moths appear during the latter part of April and 

 early May. About the first of June the moths of this first brood of the 

 season are most numerous. 



After mating takes place each female deposits several hundred eggs 

 on sugar beets or on lamb's-quarters, Russian thistle, alfalfa and other 

 plants growing in the field and along the ditch banks and fence rows. 



At the end of from three to five days hundreds of hungry little worms 

 hatch and begin their work of destruction. 



Feeding continues from two to three weeks, the amount eaten 

 daily increasing very rapidly until the worms are full grown. During 

 the last two or three days before they enter the soil to pupate, the amount 

 eaten is appalling. 



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