December, '12] PADDOCK: THE SUGAR-BEET WEB WORM 439 



that year by the web worms and it will no doubt be several seasons 

 before they occur as a pest again. 



The Moth. The moth is from 10 to 11 mm. long and spans 21 to 

 22 mm. The upper wings are dark or grayish brown and carry four 

 bands of brown. The under wings are much lighter and uniform in 

 color. Most species of moths are on the wing only after dark or in 

 twilight but this species is active at night only in its early life, never 

 after egg dt position has started. During the day the moths are very 

 active in the dense foliage, usually depositing their eggs on the under 

 surfaces of the leaves. When disturbed they make a short irregular 

 flight, usually alighting on a leaf, sometimes on the ground. They 

 are very watchful and active. 



Moths have been captured and found full of eggs, others taken at 

 the same time contained none. This would indicate a range in the 

 time of emerging or the time in reaching sexual maturity. This 

 accounts for the worms hatching at different times. The male moths 

 live but a short time; they do not apparently emerge earlier than the 

 females. The females live a few days after the eggs are deposited. 

 It has been estimated that one moth deposits from 500 to 700 eggs, 

 these mature gradually during the period of oviposition. As a rule 

 the moths appear in a field seven to ten daj^s before the worms appear. 



The Egg. The eggs are usually deposited singly, though occasion- 

 ally in rows of three or five overlapping. The egg is pearly white in 

 color, oval in form and about one mm. long and seven-tenths in diam- 

 eter. They may be found on either side of the leaf, more often on the 

 under side. After once seeing the eggs they are readily observed with 

 the unaided eye. "At the end of the second day a black speck appears 

 near one end of the egg w^iich is the head of the young worm develop- 

 ing within the egg. In three more days the little worm eats a ragged 

 exit hole in the shell and escapes." (Gillette.) 



The Larva. The young larvse are pale green, with a black head. 

 They are so small when first hatched, measuring only four mm., that 

 they are easily overlooked. Very soon the larvse construct a small 

 dense web, which serves as a protection while they are young. This 

 is used only for the first two or three days and if disturbed while out 

 feeding they will quickly draw under this web and curl up. During 

 the first two or three days the larvae eat but little and skeletonize the 

 leaves instead of devouring them. 



The mature larvce are from 15 to 21 mm. long averaging 18 mm., 

 with the head small and pointed. The body color is green with a 

 preponderance of longitudinal markings. A light strip on the dorsal 

 side carries an entire black line; the lateral stripes carry rudiments of 

 black lines. The second and third generations are much darker than 



