182 ■ OHIO EXPERIMENT STATION: BULLETIN 194. 



THE LEAF EATING INSECTS. 



^, -rrrr ■ ,^ 7 , ^ 7 Tfals inscct undoubtcdly heads the 



TAe White Marked Tussock ^.^^ ^^ leaf-eating pests found in Ohio. 



Moth, Hemerocamta leu- j^ .^ ^^^.^^ distinguished during all 



costigma Sm. & Abb. ^^^^^^ ^^ .^,^ jj^^ ^^^tox^. See Plate 5. 



Two broods occur each season, the young larvae of the first appear- 

 ing soon after the leaves are well out upon the majority of the shade 

 trees. The winter is passed in the ^ZS stage. 



The eggs are deposited upon the discarded cocoon of the female 

 moth, in a white frothy mass from J^ to 1 inch in length and varies 

 from 200 to 400 in number. The frothy aspect results from the 

 brittle material that binds the mass together. 



The larva upon first hatching is a hairy caterpillar about /^ 

 inch in length and, while young, has the power of spinning a silken 

 thread with which it lowers itself if the tree is jarred or suddenly 

 shaken by wind. Currents of air, swinging it, may deposit it upon 

 the nearby trees and this is one of the means by which the spread 

 of the insect is effected. 



The newly hatched larva feeds for a time upon the epidermis 

 of the lower side of the leaf but as it grows older and stronger more 

 of the leaf is eaten until by the time it is full grown all but the 

 midrib and larger veins are devoured* 



The grown larva is one of the most beautiful caterpillars occur- 

 ing in Ohio. The head is coral red; extending longitudinally along 

 the back is a broken black line bordered by narrower lines of 

 yellow. The yellow bands are bordered by broader ones of drab. 

 Below, the caterpillar is yellow. Projecting forward like horns 

 just above the head are two black tufts of hair Yi or more the length 

 of the body, and extending from the opposite end is a single tuft of 

 the same textu-re, though not quite so long. On the dorsal side of 

 the 4th, Sth, 6th and 7th segments are compact tussocks of pure 

 white hair and on account of this the insect is called the Tussock 

 Moth. The larval stage is of a little over a month's duration. Upon 

 the completion of larval growth the caterpillars become abnormally 

 -active, crawling about, seeking a suitable place to pupate. During 

 their wanderings they may travel considerable distances and it is 

 mainly at this time that the advance from tree to tree is 

 effected. 



After a satisfactory place has been found in which to pupate, 

 the larva constructs for itself a cocoon, mainly from the hairs of its 

 own body. About two weeks are spent in the pupal stage at the 

 the termination of which the adults appear. The adult female is 



