TIMBER; FORESTRY 



123 



6. Wood-boring and leaf-eating insects should be killed, 

 if the expense of the process is not too great. It is suggested, 

 for example, that the great damage caused by the spruce- 

 destroying beetle, which kills mature trees by mining the bark 

 of the trunk, may be much lessened. This can be accomplished 

 by cutting and removing most of the infested trees or by gir- 

 dling trees early in June, to expose them to the attacks of the 

 beetles, then felling and either peeling 

 them or immersing them in water, to 

 destroy the insects before the new crop 

 of beetles emerges from under the bark 

 the following June. 1 



One of the most effectual means of 

 destroying some injurious insects con- 

 sists in introducing into the region where 

 they abound parasitic or other insects 

 which will kill great numbers of the 

 objectionable species. Plant lice, for in- 

 stance, are thus killed by ladybugs. 

 Vigorous attempts are now being made 

 to exterminate the gypsy moth in New 

 England by means of parasites and by 

 carnivorous insects (fig. 100) which at- 

 tack and kill the moth at some stage of 

 its existence. The caterpillars of this 

 moth are extremely destructive to many kinds of trees, which 

 they strip of their leaves in a short time. More than a million 

 dollars has probably been expended in Massachusetts alone in 

 trying to get rid of this pest. The moth was introduced into 

 America in 1869, by a scientist who lived at Medford, near 

 Boston, in the course of some most unfortunate experiments 

 on silk-producing insects. 2 



1 See "Insect Enemies of the Spruce in the Northeast," Bulletin 28, 

 New Series, Division of Entomology, U.S. Dept. Agr., 1901. 



2 "The Gypsy Moth in America," Bulletin 11, New Series, Division of 

 Entomology, U.S. Dept. Agr., 1897. 



FIG. 100. A carnivorous 

 beetle (Calosoma syco- 

 phanta) which destroys 

 the caterpillars of the 

 gypsy moth 



These beetles have been 

 imported from Europe, 

 and successful colonies of 

 them established in New 

 England. After United 

 States Department of 

 Agriculture 



