No. 4.] THREE SHADE-TREE INSECTS. 243 



wholly exempt from the ravages of this beetle, while in 

 some cases the sugar and red maples and hickories were 

 attacked either by this insect or by one of identical habits. 

 The presence of the borer is shown by the falling of living 

 branches which have been severed from the tree by a clean 

 cat. By splitting the severed end of a fallen branch the 

 insect causing the damage may be readily found, — a slender 

 white or yellowish- white grub with black mouth parts. 



Life History. 



The eggs are said to be laid by the parent beetle in early 

 summer upon the young growing lateral twigs, at a distance 

 varying from a few inches to a foot or more from 

 the main branch. Probably but a single e^g is 

 laid on each lateral twig. Upon the hatching of 

 the Q2,^ the young grub or larva burrows down- 

 ward in the twig, leaving but a thin shell of bark 

 and wood. When the branch is reached a burrow ^^^- *• ^ak 



Pruner.* 



is made beneath the bark for a short distance 

 toward the trunk, and the branch is nearly cut off by the 

 larva. The latter then retreats into its burrow, plugs it 

 with chips and feeds within the branch. Winds soon break 

 the weakened branch from the tree, and in the fallen branches 

 the larvse feed until fall, when the majority transform into 

 pupse from which the mature beetles emerge the following 

 spring. 



Concerning the time occupied by this borer in passing 

 through its various transformations there are many state- 

 ments of a contradictory character. It would appear that the 

 time may vary from one to four years, although the writer 

 believes that one year is the rule in this region. Dr. Hamil- 

 ton, f in his criticism of the writings of Peck, Harris and 

 Fitch on this insect, states that in cases coming under his 

 observation from three to four years were required for the 

 development of the mature insect. In the summer of 1896 

 a number of branches infested by this insect, collected soon 

 after falling from the trees, were placed in an out-door 

 breeding cage at the insectary of the gypsy moth committee, 



* Drawn by J. H. Emerton. t Canadian Entomologist, August, 1887. 



