94 FALSE PARASITES 



little band of from ten to twelve caterpillars (prob- 

 ably relatives) keep together on a twig, and eat 

 during night and day^ They grow rapidly, learn 

 to move more quickly, upwards of one hundred 

 and more uniting, and forming a wandering colony, 

 in order to attack larger branches. They wander 

 thus from twig to twig, casting their skin for the 

 first time towards the end of May, by rubbing 

 against the uneven bark of the oak. They are 

 now of from one-third to one-fourth of an inch 

 long, of a gray color, distinctly showing twelve 

 segments, and on the top of each segment a black 

 shield, with very short, velvet-like hair, of a pecu- 

 liar lustre. The large hairs are ranged in from 

 two to three bunches on each segment, having 

 lower down on their sides eight spiracles, and eight 

 pairs of legs. 



During the time of the casting off of the skin, 

 the gray caterpillar becomes yellowish-brown, 

 lustreless, stronger, but lazier. The caterpillars 

 mostly gather where a branch withers, and attach 

 themselves so firmly by spinning a cocoon, that 

 caterpillar and bark seem one. The cocoon is 

 thin and transparent, and attached to its inner 

 part is the cast skin. These caterpillars have quite 



