72 INSECTS OF MASSACHUSETTS. 



alighting on some tree or wall, or dropping to the ground. If we 

 go to an old pine-tree we may discover from whence they have 

 come, and what they have been about during the past period of 

 their lives. Here they will be found creeping out of thousands of 

 small round holes which they have made through the bark for 

 their escape. Upon raising a piece of the bark, already loosened 

 by the undermining of these insects, we find it pierced with holes 

 in every direction, and even the surface of the wood will be seen 

 to have been gnawed by these little miners. After enjoying 

 themselves abroad for a few days, they pair, and begin to lay 

 their eggs. The pitch-pine is most generally chosen by them for 

 this purpose, but they also attack other kinds of pines. They 

 gnaw little holes here and there through the rough bark of the 

 trunk and limbs, drop their eggs therein, and, after this labor is 

 finished, they become exhausted and die. In the autumn the 

 grubs hatched from these eggs will be found fully grown. They 

 have a short, thick, nearly cylindrical body, wrinkled on the back, 

 are somewhat curved, and of a yellowish white color, with a horny 

 darker colored head, and are destitute of feet. They devour 

 the soft inner substance of the bark, boring through it in various 

 directions for this purpose, and, when they have come to their full 

 size, they gnaw a passage to the surface, for their escape after they 

 have completed their transformations. These take place deep in 

 their burrows late in the autumn, at which time the insects may be 

 found in various states of maturity, within the bark. Their depre- 

 dations interrupt the descent of the sap, and prevent the formation 

 of new wood ; the bark becomes loosened from the wood, to a 

 greater or less extent, and the tree languishes and prematurely 

 decays. The name of this insect is Hylurgus terebrans*, the 

 boring Hylurgus ; the generical name signifying a carpenter, or 

 worker in wood. It belongs to the family Scolytid^e, including 

 various kinds of destructive insects, which may be called cylindri- 

 cal bark-beetles. The insects of this family may be recognised 

 by the following characters. The body is nearly cylindrical, ob- 

 tuse before and behind, and generally of some shade of brown. 

 The head is rounded, sunk pretty deeply in the forepart of the 

 thorax, and does not end with a snout ; the antennae are short, 



Scolytus terebrans of Olivier. 



