THE FALL WEBWORM SNODGRASS. 401 



By the end of two weeks from the hatching most of the caterpillars 

 of Stage II reach a length of nearly one-fifth of an inch and have 

 changed somewhat in appearance. The general color of the body 

 is of a deeper tone, and there are suggestions of lengthwise stripes 

 formed by rows of dark brown patches on the skin between the tu- 

 bercles along the sides of the back, while a series of blotches on the 

 middle of the back suggests a median dorsal stripe. Soon after this 

 the second molt takes place and the caterpillars appear in Stage III. 

 The general tone of the body color is now still darker than before, 

 and the hairs are more abundant, with a greater number of the soft, 

 pale gray ones, which gives the creatures a woolier appearance, 

 though the large tubercles along the sides of the back bear now each 

 3 to 5 black hairs instead of one. The brown blotches on the back 

 have enlarged and run together, forming a distinct, dark dorsal band. 

 Just before each molt the caterpillar takes a premolting siesta lasting 

 about 24 hours; and after the change it still sits around in a sleepy 

 mood for several hours, but when this wears off it takes its place with 

 the active ones. 



The webs grow rapidly during Stage III, but the general routine 

 of life is the same as before. Perhaps a greater number of cater- 

 pillars now work on the outside, and in this stage the writer has 

 noticed them first feeding on the under surfaces of the leaves through 

 the outer walls of the tent. This practice is more common with some 

 colonies than with others. 



x\bout 18 days from the date of hatching the first appear in Stage 

 IV. The longest are now three-eighths of an inch in length with 

 hairs much longer and more numerous than before and the general 

 appearance still woolier. The color pattern has not changed much, 

 but the lines are darker, and the dorsal stripe is particularly conspicu- 

 ous as a continuous blackish band from the dark head and thoracic 

 plates in front to the prominent black dorsal tubercles of the twelfth 

 segment and the back plate on the thirteenth. The under surface is 

 pale greenish, stippled with brown; the thoracic legs are black, the 

 abdominal legs blackish. 



The web may still be a flimsy affair, straggling from leaf to leaf 

 or from one twig to another, but Stage IV is one of the busiest 

 periods of the caterpillars' lives. Toward the end of it they reach a 

 length of five-twelfths of an inch and the webs attain a size that 

 makes them begin to be noticeable objects in the trees. Individual 

 tents may be a foot or more in diameter while deserted chambers and 

 connecting canopies spread out over an extensive area. The size of 

 the web depends on the size and vigor of the colony. Sometimes an 



