312 INSECT ARCHITECTURE. 



ponding with this glutinous matter, while they ex- 

 clude every fluid of a different quality."* When 

 confined in an open glass vessel, the goat-moth cater- 

 pillar will efl'ect its escape, by constructing a curious 

 silken ladder as represented by Roesel. 



Caterpillars, as they increase in size, cast their 

 skins as lobsters do their shells, and emerge into re- 

 newed activity under an enlarged covering. Previous 

 to this change, when the skin begins to gird and 

 pinch them, they may be observed to become languid, 

 and indifferent to their food, and at length they cease 

 to eat, and await the sloughing of their skin. It is 

 now that the faculty of spinning silk seems to be of 

 great advantage to them; for being rendered inac- 

 tive and helpless by the tightening of the old skin 

 around their expanding body, they might be swept 

 away by the first puff of wind, and made prey of by 

 ground beetles or other carnivorous prowlers. To 

 guard against such accidents, as soon as they feel 

 that they can swallow no more food from being half 

 choked by the old skin, they take care to secure 

 themselves from danger by moorings of silk spun 

 upon the leaf or the branch where they may be re- 

 posing. The caterpillar of the Avhite satin-moth 

 (^Leticomas salicis, Stephens) in this way draws to- 

 gether with silk one or two leaves, similar to the leaf- 

 rollers (Torlricid(ti), though it always feeds openly 

 without any covering. The caterpillar of the puss- 

 moth again, which, in its third skin, is large and 

 heavy, spins a thick web on the upper surface 

 of a leaf, to which it adheres till the change is 

 effected. 



The most important operation, however of silk- 

 spinning is performed before the caterpillar is trans- 

 formed into a chrysalis, and is most remarkable in 

 the caterpillars of moths and other four-winged flies, 



* Spectacle de la Nature, vol. i. 



