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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



V (fig. 7) the colors are much brighter and more strongly contrasted 

 than in the earlier stages. The black dorsal band bordered by the 

 black tubercles along the sides of the back is now very conspicuous. 

 The tubercles on the sides are orange. A lemon yellow band runs 

 between the line of the black marginal tubercles of the back and that 

 of the uppermost row on the side; while a broken white line runs 

 between the second and third rows on the side. The ground color of 

 the sides is greenish gray, stippled with black; the under parts are 

 drab with black stippling; the thoracic legs and the bases of the ab- 

 dominal legs are black. The hairs are now longer and more abundant 



than ever, and the soft pale gray ones are 

 particularly noticeable. The intensity 

 of the colors varies much in different 

 individuals, but the features described 

 are characteristic of this stage and are 

 intensified in the next. The caterpillars 

 themselves are active, fine-looking, long- 

 haired fellows, about three-fourths of an 

 inch long. They run rapidly with a 

 noticeable humping motion of the body. 

 The webworms seem to be creatures 

 possessed with a spinning mania or an 

 insatiable desire to work for work's sake. 

 Either the weaving instinct is overde- 

 veloped or it has survived a time when 

 it served a greater need than at present, 

 for the caterpillars continually elaborate 

 the walls of their houses, although they 

 are already fulfilling every purpose of 

 their construction. Moreover, the webs 

 are so soon to be deserted that such sub- 

 stantial building looks superfluous, and 

 the inhabitants often move on to a new 

 place from a web that still contains an abundance of fresh, uneaten 

 leaves. Yet, even when the provisions in an old tent are entirely gone, 

 a few caterpillars will always stay with it, working away on the walls 

 and framework as if building a memorial for all time. By night as 

 well as by day work goes on. Irate on warm nights, in the illumina- 

 tion of a lantern or a flash light, one may see the busy laborers swaying 

 and twisting or dangling in mid-air in all kinds of perilous attitudes 

 on invisible scaffoldings against the sky. Yet there are occasional 

 periods of rest, besides those accompanying the molts, when all the 



Fig. 7. — Webworm in Stage 

 (natural length 2 inch). 



