86 
COLEOPTE BA. 
tion of new wood ; the bark becomes loosened from the wood, 
to a greater or less extent, and the tree languishes and prema- 
Fig. 42 . turely decays. The name of this insect is Hylur- 
(jus terebrans * the boring Hylurgus (Fig. 42) ; the 
generical name signifying a carpenter, or worker in 
wood. It belongs to the family Scolytidje, includ- 
ing various kinds of destructive insects, 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 
following 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 extremity 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 produc- 
tive 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 subject 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 Sculytus destructor, of which an interesting 
Stolytus terebrans of Olivier. 
