Insect Study 



331 



The cecropia cocoon is found most abundantly on our orchard and 

 shade trees; it is called by the children the "cradle cocoon,'' since it is 

 shaped like a hammock and hung close below a branch, and it is a very 



safe shelter for the helpless creature within it. 



It is made of two walls of silk, the outer one being 

 fe^^ Bfe thick and paperlike and the inner one thin and 



mffk ^^ firm; between these walls is a matting of loose 



' " silk, showing that the insect knows how to 



make a home that will protect it from winter 

 weather. It is a clever builder in another 

 respect, since at one end of the cocoon it spins 

 the silk lengthwise instead of crosswise, thus 

 making a valve through which the moth can 

 push, when it issues in the spring. It is very 

 interesting to watch one of these caterpillars 

 spin its cocoon. It first makes a framework by 

 stretching a few strands of silk, which it spins 

 from a gland opening in the lower lip; it then 

 makes a loose net-work upon the supporting 

 strands, and then begins laying 

 on the silk by moving its head 

 back and forth, leaving the sticky 

 thread in the shape of connect- 

 ing M's or of figure 8's. Very 

 industriously does it work, and 

 after a short time it is so screened 

 by the silk, that the rest of 

 its performance remains to us 

 a mystery. It is especially 

 mysterious, since the inner wall 

 of the cocoon encloses so small a cell that the caterpillar is obliged 

 to compress itself in order to fit within it. This achievement 

 would be something like that of a man who should build around 



The eggs of the cecropia 



moth. 

 Photo by M. V. Slingerland. 



The cecropia caterpillar molting. 



Photo by M, V, Slingerland, 



Full-grown cecropia caterpillars. 

 Photo by M. V. Slingerland. 



