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CHAPTER XYII. 



STRUCTURES OF SILK SPUN BY CATERPILLARS, INCLUDING THE 

 SILK-WORM. 



" Millions of spiuning-worms, 

 That in their green shops weave the smooth-hair'd silk." 



Milton's Comus. 



All the caterpillars of butterflies, moths, and, in general, 

 of insects with four wings, are capable of spinning silk ; 

 of various degrees of fineness and strength, and differing 

 in colour, but usually white, yellow, brown, black, or grey. 

 This is not only of advantage in constructing nests for 

 themselves, and particularly for their pupse, as we have so 

 frequently exemplified in the preceding pages, but it 

 enables them, the instant they are excluded fiom the egg, 

 to protect themselves from innumerable accidents, as well 

 as from enemies. If a caterpillar, for instance, be exposed 

 to a gust of wind, and blown off from its native tree, it lets 

 itself gently down, and breaks its fall, by immediately 

 spinning a cable of silk, along which, also, it can reascend 

 to its fijrmer station when the danger is over. In the 

 same way, it frequently disappoints a bird that has marked 

 it out for prey, by dropping hurriedly down from a branch, 

 suspended to its never-failing delicate cord. The leaf- 

 rollers, formerly described, have the advantage of other 

 caterpillars in such cases, by being able to move as quickly 

 backwards as forwards ; so that when a bird puts in its 

 bill at one end of the roll, the insect makes a ready exit at 

 the other; and drops along its thread as low as it judges 

 convenient. We have seen caterpillars drop in this way 

 from one to six feet or more ; and by means of their cable. 



