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 Hjlurgus 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 

 jmcldy, and has reference to minute elevated j)oints on the elytra. It is 

 a tenth of an iuch 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 antennsB are reddish. This little insect is often seen 

 in the first warm days of spring sunning 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 oft' obliquely and sur- 

 rounded with a number of short spines. Thfey 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. pint, three-twen- 

 tieths of an inch 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, Geofi'roy, is distinguished by the singular formation of the 

 abdomen, which is abruptly turned upwards on the under or ventral 

 side, beyond the first segment. The head is usually flattened, and either 

 striated or rougbly 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 A-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 inch in length, sometimes wholl}' 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 larvae of 

 these little beetles. They work between the bark and the wood, cutting 

 divergent furrows, as shown in the accompanying figure, and finally 



