AGRICULTCRAX EXPERIMENT STATION. 



125 



size bj' additional layers of silk as the vrorms grow, until it is some- 

 times ten inches or more across. The worms remain in the tent at 

 night, during stormy weather and when not feeding, unless the weather 

 is warm, when they may be seen upon the outside literall}- covering 

 the web. They march in military order twice a day from the nest to 

 feed, once in the morning and once in the afternoon. They pave their 

 roads with silk and follow along them to the leaves. When mature 

 each worm will consume two leaves a day and an average of five 

 hundred leaves would be required for a colon}-. There are often 

 several webs in a tree. The effects are to rapidly defoliate the tree 

 and draw heavily upon its vitality to produce new leaves. The 

 caterpillars require about six weeks to mature and are then about 

 an inch and three-fourths long, and have the appearance shown in 

 Fig. 11, a and b. The worms have a " white line along the back ; 

 then a yellow line dotted with black ; then a black stripe marked 

 with blue aud yellow dots ; then a wav}' yellow line dotted with 

 black ; then a blue stripe dotted with yellow ; then a broken white 

 line ; bead black ; under side of body black ; the body covered with 

 yellowish or whitish hairs." 



FIG. H. 





When mature, the larvae 

 leave the trees and wander 

 about in search of a place 

 to spin their cocoons. They 

 prefer the loose bark of 

 trees, the under side of 

 fence caps and will enter 

 sheds and porches and 

 climb the sides of houses 

 and transform under the 

 edge of clapboards, win- 

 dow caps and eavea. "When 

 the orchard is near they 

 become a nuisance by en- 

 tering the house. 



Cocoon — Oblong, oval, 

 light yellow, formed of a 

 loosely woven outer cov- 

 ering and a dense tough 

 inner coat. The larva en- 



