SHORT-HORNED WOOD-BORERS. 
147 
account of its habits is given in Dr. Harris’ Treatise. A much smaller 
species, the H. dentatus, Say, often bores innumerables holes in the red 
cedar. 
We have ten described species of Hylesinus , Fab. Whilst the species 
of Hylurgus and Tomicus are found in evergreens, and especially in the 
different kinds of pine, the species of Hylesinus and Scolytus inhabit 
mostly, if not exclusively, the hard-wooded deciduous trees. The most 
common species is the H. aculeatus , Say. The specific name means 
prickly, and has reference to minute elevated points on the elytra. It is 
a tenth of an inch in length, or a little more, of a blackish- brown ground 
color, but largely varied with ash color, produced by microscopically 
minute scales. The top of the thorax is bare, leaving a. large elliptical 
blackish spot. The antennae are reddish. This little insect is often seen 
in the first warm days of spring sunuing itself upon stumps or fences 
which run through timbered land. I have found it abundantly in wood 
which appeared to be that of some species of poplar. 
In Tomicus , Latr., the tip of the abdomen is cut off obliquely and sur- 
rounded with a number of short spines. They are all of a reddish or 
chestnut color. Three of the species are frequently met with in pine 
forests, all of which were originally described and named by Mr. Say. 
They are the T. exesus, upwards of two-tenths of an inch in length, with 
six or eight points at the tip of each elytron ; the T. pini, three-twen- 
tieths of an iuch long, the tip of each elytron about four-toothed; and 
the T. xylographus, but little more than a tenth of an inch long, the ely- 
tra but slightly truncated, puncto-striate, with minute points on the pos- 
terior declivity, between the punctures. 
Scolytus, Geoffroy, is distinguished by the singular formation of the 
abdomen, which is abruptly turned upwards on th^ under or ventral 
side, beyond the first segment. The Jiead is usually flattened, and either 
striated or roughly punctured on top, and surrounded with a coronet of 
incurved hairs. They inhabit, as we have above stated, the hard-wooded 
trees. European species live in the oak, the elm, the ash, and the plum. 
The different kinds of hickory, including the shell-bark, the bitter-nut, 
and the pecan, are extensively damaged by the Scolytus 4-spinosus, Say, 
so-called on account of four short spines at the tip of the abdomen of 
the males. The turned up portion of the venter is moreover deeply con- 
cave in this sex, and divided down the middle by a carina, or ridge. It 
is nearly two-tenths of an iuch in length, sometimes wholly black, but 
the elytra are often reddish-brown. The females are about a quarter 
part smaller, and the venter is but slightly concave, and without either 
spines or carina. In many groves of timber in Northern Illinois, the 
bitter-nut hickories have been completely destroyed by the larv® of 
these little beetles. They work between the bark and the wood, cutting 
divergent furrows, as shown in the accompanying figure, and finally 
