52 



ENTOMOLOGICAL SOCIETY OF ONTARIO. 



Tussock Moth. 



Orgyia leucostigma. 



The Tussock moth is another insect pest which has attracted considerable attention 

 during July, 1896. Though not widespread in its attack, it has occupied considerable 

 space in the newspapers. 



Its ravages have been largely confined to the defoliation of shade trees in the city 

 of Toronto, and hence, appearing at a place where important daily papers are published, 

 it received much notice. 



Although in Toronto this caterpillar confined itself largely to an attack upon the horse- 

 chestnut trees, yet it feeds upon the foliage of other trees. It has been found doing much 

 injury to the elm and apple, and also feeding upon the plum, pear, maple, oak, walnut, 

 butternut, locust and spruce. Few, if any trees, are exeaipt from its attack. It mide 

 its appearance in Toronto about July 1st, and remained for about three weeks, during 

 which time it defoliated many of the horse-chestnut trees on Jarvis street, College avenue 

 and in some other parts of the city. The writer visited the city July 27tb, and had an 

 opportunity to investigate its ravages. 



This insect is readily identified in all its stages — egg, larva, pupa and imago. 



Fig. 51. 



Fig. 52. 



Fig. 53. 



Fig. 54. 



Orgyia leucostigma. a Adult female on cocoon, b Young larva, c Female 

 pupa, d Male pupa, e Adult male (after Riley). 



The eggs appear in masses (400-700) covered with a froth-like substance, that dries 

 and hardens upon them, and serves to protect them from injury by the weather (rain), 

 predaceous insects, and even birds. This covering is very white, and thus renders the 



Fig. 55. 0. leucostigma, full-grown larva (after Riley). 



egg masses quite conspicuous at a considerable distance whera they are deposited. These 

 masses may be found on the trunk of the trees, in crevices of the bark, on the larger 

 limbs, or in sheltered spots, such as fence boards and on bunches of dead leaves hanging 

 upon the tree. In Toronto, the trunks of the horse-chestnut trees attacked presented in 

 some cases quite a spotted appearance, from the innumerable white masses of eggs and 

 cocoons attached to the bark. 



As soon as the eggs hatch, tiny caterpillars (fig. 51, b) make their appearance (usually 

 about June), and, as development proceeds, they pass through a series of molts, three — (one- 



