3-16 Canadian Record of Science. 



The female generally selects a forked twig of willow or 

 poplar and oviposits about 400 beautiful pale j^ellow eggs, 

 resembling minute musk melons. These eggs hatch about 

 June 6th into little dull orange caterpillars sparsely cov- 

 ered with brown hairs ; in the later moults these hairs 

 change into black branched spines. 



These caterpillars are very irritable little creatures, 

 throwing up their heads in a threatening manner when 

 one approaches too near them. They spin a line of silk 

 behind them as they walk in search of a fresh leaf, these 

 strands probably serving as life lines in preserving them 

 from injury from a fall, or it may be these form a system 

 of telegraphic wires. 



After feeding for four or five days the old skin gets too 

 small and requires to be shed. One can easily tell the 

 time of moulting by their sullen, dissatisfied attitude ; 

 this period continues for a day or two, when they manage 

 by a lot of wriggling to get rid of the worn-out skin. 

 After the first moult the caterpillars present a little 

 improved appearance. The head is black, with two rows 

 of interrupted brown lines down the back and several 

 black hairs on each segment, each tipped with a white 

 hair. The description of tlie four succeeding moults is so 

 similar that it will only be necessary to describe the 

 last one. 



Fifth moult. — Length two inches, witli four branched 

 spines, innumerable white hairs in between, and a reddish 

 irregular-shaped spot on each segment down the back. 

 The six front legs are black, prolegs Indian red, and anal 

 ones black. These caterpillars do considerable damage 

 sometimes to elm and various other trees, including poplar, 

 willow and hop. 



The next stage requires unusual gymnastic accomplish- 

 ments which would drive a modern acrobat green with 

 envy. The first thing it does is to spin a button of silk 

 (under a ledge of a fence or a branch), tuck its two anal 



