Chapter IV. 



INSECTS INJURIOUS TO THE LOCUST TREE. 



(Robinia pseudacacia.) 



Of insects feeding upon the locust forty-one species are here re- 

 corded. By far the most pernicious borer in the trunk and the most 

 deadly enemy of the tree is the locust borer, the first mentioned below. 

 The twigs are often swollen and disfigured by the locust twig-borer. 

 We have observed the leaves to be most damaged by the Depressaria 

 caterpillar. The other insects mentioned below are more or less pecul- 

 iar to the tree, and at certain times may be locally destructive. 



AFFECTING THE TRUNK. 



1. The locust borer. 



Cyllene rohinice (Forster). 



Order Coleoptera ; family Cerambycid^. 



Boring a bole one-quarter of an incii in diameter under the bark and upwards, 

 deep into the wood, and ejecting the dust through the orifice in the bark, a longi- 

 corn larva, which transforms to a pupa iu its burrow, and late in summer appears as 

 a brown beetle, striped and banded with golden yellow, and with a VV oil 'ts wiug- 

 covers; often abundant on the flowers of the golden rod early in September, when 

 they lay their eggs iu crevices in the bark of the locust. 



This is by far the most destructive pest of the locust, one of the 

 most beautiful and valuable of our shade trees. In New England there 

 is scarcely a tree which does not show tlie marks of its attacks, and in 

 many localities it has practically been exterminated. In the Western 

 States it is also very destructive ; but from observations we made in 

 Kentucky iu 1874 the noble locust trees in that State had grown so lux- 

 uriously as to apparently escape or overcome the insidious attacks of 

 this borer. It occurs throughout the United States east of the Plains. 



The operations of the grub or larva may be detected by a mass of 

 sawdust like castings at the mouth of its gallery. 



The beetles are abundant, feeding on the flowers of the golden rod 

 (Solidago), early in September, when we have taken them in Cambridge, 

 Mass., and at Providence, E. I. So wide are the deep yellow spots and 



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