FOREST INSECTS 85 



branches and trunk of a great variety of trees and shrubs. 

 The parent moth deposits great numbers of eggs in the crev- 

 ices of the bark, and the larvae on hatching migrate to the 

 tips of the branches where they enter small twigs. In these 

 they construct a small circular burrow till they have in- 

 creased too much in size to remain within the twig. They 

 then leave it to enter a more commodious small branch, 

 and may thus move into larger quarters several times before 

 completing their growth. This requires two or three seasons 

 and the large caterpillars often partially girdle large branches 

 or the trunks of small trees, by tunnelling transversely 

 through the superficial sapwood and inner living bark. The 

 leopard moth slowly spread along the Atlantic seaboard after 

 its establishment on Long Island, and has proved itself to be 

 practically omnivorous, as one entomologist found it attack- 

 ing over 150 different kinds of shrubs and trees. Although 

 commonly found in many healthy and rapidly growing trees, 

 it seems to be particularly attracted to elms that are not in 

 prime condition. As a consequence it has found trees weak- 

 ened by the elm leaf-beetle greatly to its liking and has fol- 

 lowed the beetle very generally, reducing the vitality of the 

 elms to a still lower ebb. At the present time the leopard 

 moth occurs in America in only a very limited region from 

 New Jersey to Massachusetts, but it is undoubtedly destined 

 to cross the entire continent in the future. 



Still more recently a third European insect enemy of the 

 elm has been noticed in this country. This is a small bark- 

 beetle (Eccoptog aster multistriata) , which made its appearance 

 in the vicinity of Boston about 1906. Its habits are similar 

 to those of the Dendroctonus beetles so destructive to conif- 

 erous trees, but the elm bark-beetle attacks only sickly trees, 

 or the dying branches of more prosperous ones. After the 

 manner of many other bark-beetles, large numbers of individ- 

 uals commonly center their activities upon selected trees 

 which have their inner bark riddled by the burrows of the 

 beetles. Trees weakened by the leopard moth are very sus- 

 ceptible to their attacks and succumb rapidly. Where the 

 beetles are not checked by preventive measures they may 



