402 ANNUAL REPOBT SMITHSONIAN INSTITUTION, 1921. 



original colony splits up into two or more groups, and sometimes 

 neighboring colonies unite, even though the members are in different 

 stages. 



Most of the time the worms are very sedate and businesslike in 

 their actions, but sometimes as you watch a colony of caterpillars at 

 work, all spinning and weaving as if they have not a moment to 

 waste, suddenly, every individual rears up and violently wags its 

 forward half, swinging from side to side with quick, short jerks. 

 You had probably done nothing to provoke this curious demonstra- 

 tion, and probably if you try to make the creatures do it again by any 

 sort of disturbance they will quietly proceed with their spinning or 

 their eating. The writer has kept colonies indoors and many times 

 watched them perform this wagging ceremony, but has not been able 

 to discover a motive or in most cases any reason for it. A crowd of 

 young caterpillars sometimes wags shortly after hatching, some 

 colonies seldom do it at any age ; one was observed for 27 days before 

 a wagging exhibition was noted. Others wag at frequent intervals. 

 As if at some signal the absurd performance begins and is taken up 

 simultaneously by all members of the colony whether inside the tent 

 or without and whether feeding or spinning. You may touch and 

 annoy an individual caterpillar and the insignificant creature reels 

 about, bites at your finger, and emits a drop of yellow liquid from its 

 mouth to indicate its resentment; you may tap the nest or jar the 

 tree without effect ; but again, while all is calm and peaceful, suddenly 

 for no apparent reason, uprears every worm and wags. One sure 

 stimulus, however, that will always start the performance, is tobacco 

 smoke — ever so little wafting over a tent sets all the occupants into 

 energetic vibration. Whether the action registers disapproval or 

 pleasure one can not say. 



As the caterpillars become older an increasing number of them 

 spend their time on the outside of the tent and feed on the lower 

 epidermis of the leaves through the web. Some colonies that the 

 writer studied in Indianapolis appeared to live during the fourth 

 and fifth stages very largely on the exterior of the tents and did most 

 of their feeding on the outside. These used the interiors principally 

 as molting chambers, though an occasional individual even sheds its 

 skin on the roof of the house. Colonies observed in Connecticut, 

 however, lived almost entirely inside, except for the necessary 

 amount of external spinning, and members were seldom seen feeding 

 through the outer web. 



It is interesting to watch the behavior of a colony during a rain. 

 The caterpillars appear to feel the approach of a storm. During the 

 sultry prelude, when the thunder is growling in the on-coming cloud 

 bank, the writer has noted a complete surcease from work and has 



