154 arthropods: insects. 



these correspond to the salivary glands. The silk is 

 a sticky fluid, which hardens into a thread as soon as 

 it comes to the air. Some caterpillars spin but little 

 silk, others produce it in abundance. 



Caterpillars change their skins about four times in 

 coming to their full growth as caterpillars ; and when 

 about to change into the pupa or chrysalis state, they 

 cease eating, and many of them spin around their body 

 a silken covering called a cocoon, others suspend them- 

 selves by silken threads without making a cocoon, and 

 others enter the ground. When the caterpillar is pre- 

 pared for the change, it bursts the skin on the back, 

 draws out the forward part of its body, and works the 

 skin backward until it throws it off ; and now it is a 

 chrysalis, shorter than the caterpillar, and at first sight 

 it appears destitute of head and limbs; but on looking 

 more carefully we perceive traces of head, tongue, 

 antennae, wings, and legs. Some chrysalides are angu- 

 lar, but most of them are smooth, rounded at one end, 

 and tapering at the other ; they remain motionless, or 

 only move the hind part of the body when touched. 

 At length, the inclosed insect is ready to come forth, 

 and by many movements its bursts the skin of the 

 back, and the Butterfly or Moth appears. At first it 

 is soft, weak, and moist, with small and shriveled 

 wings; but soon the moisture passes off, the limbs 

 become firm, the wings expand, and the perfect and 

 beautiful insect flies away to feed upon water and the 

 honey of flowers. Butterflies and Moths do not in- 

 crease in size ; the_\' are full grown when they emerge 

 from the pupa skin ; and after having laid their eggs, 

 they soon die. Butterflies fly in the daytime, have 

 their wings erect when at rest, their antennse are 



