76 INSECTS INJURIOUS TO VEGETATION. 



vent the formation of new wood; the bark becomes loosened 

 from the wood, to a greater or less extent, and the tree lan- 

 guishes and prematurely decays. The name of this insect is 

 Hi/Iurg-us terebrans* the boring Hylm-gus ; the generical name 

 signifying a carpenter, or worker in wood. It belongs to the 

 family Scolytid^e, including various kinds of destructive in- 

 sects, which may be called cylindrical bark-beetles. The 

 insects of this family may be recognized by the following 

 characters. The body is nearly cylindrical, obtuse before and 

 behind, and generally of some shade of brown. The head is 

 rounded, sunk pretty deeply in the fore part of the thorax, and 

 does not end with a snout; the antennae are short, more or less 

 crooked or curved in the middle, and end with an oval knob; 

 the feelers are very short. The thorax is rather long, and as 

 broad as the folloAving part of the body. The wing-covers are 

 frequently cut off obliquely or hollowed at the hinder extremity. 

 The legs are short and strong, with little teeth on the outer 

 edge or exti-emity of the shanks, and the feet are not wide and 

 spongy beneath. 



Though these cylindrical bark -beetles are of small size, they 

 multiply very fast, and where they abound are productive of 

 much mischief, particularly in forests, which are often greatly 

 injured by their larvae, and the wood is rendered unfit for the 

 purposes of art. In the year 1780, an insect of this family 

 made its appearance in the pine-trees of one of the mining 

 districts of Germany, where it increased so rapidly that in 

 three years afterwards whole forests had disappeared beneath 

 its ravages, and an end was nearly put to the working of the 

 extensive mines in this range of country, for the want of fuel 

 to carry on the operations. Pines and firs are the most sub- 

 ject to their attacks, but there are some kinds which infest 

 other trees. The premature decay of the elm in some parts 

 of Europe is occasioned by the ravages of the Scolytus de- 

 structor^ of which an interesting account was ^vritten in 1824, 

 by Mr. Macleay. An abstract of his paper may be found in 



* Scolytus terebrans of Olivier. 



