OTHER INSECTS OF SPECIAL INTEREST 225 
of shade trees and fruit trees. They change their color almost 
every time they change their skin, but when full grown (about 
three inches long) they are green and have many bright 
colored warts and bristles upon them. The two species 
differ in the details of these markings, so that they can easily 
be distinguished by the aid of some of the books devoted 
to the subject of moths and butterflies. 
The cocoons of these moths may be found in the fall and 
winter, put into a box with a wire netting cover, and kept 
in a cool place until spring. In a warm room the moths are 
apt to perish or else come out before the proper time. When 
it is thought that they may come forth, they should be placed 
where they can be watched carefully, for the process is a very 
interesting sight. A scraping sound within gives warn- 
ing of the coming event. 
It is also a good plan to cut open one of the cocoons, being 
very careful not to hurt the inmate. Take it out and place 
it in a wide-mouthed bottle or fruit jar and watch for the 
change from pupa to adult. As the creature is much safer 
in the cocoon than out of it, this operation should be post- 
poned until it is thought to be nearly time for the adult to 
appear. 
It is easy to see that the cocoon affords protection from 
cold and dampness as well as from birds and other possible 
sources of danger. Notice the fine silk threads of which it 
is made. The polyphemus cocoon furnishes 800 feet of good 
silk thread when softened and unwound, and a very hand- 
some and desirable silk cloth may be made from it. The 
only reason that these moths are not regularly employed 
for this purpose is that they are not so easily cared for as 
the Chinese species, which has been domesticated for many 
centuries. 
