SHORT-HOENED WOOD-BORERS. 147 



account of its habits is given in Dr. Harris' Treatise. A nuicli smaller 

 species, the H. dcntatus, Say, often bores iunumerables holes in the red 

 cedar. 



We have ten described species of IlyJesinus, Fab. Whilst the species 

 of llylnrgus and Tomicus are found in evergreens, and especially in the 

 difterent 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 R. 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 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 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 INIr. 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. j^ini, 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, Geoftroy, 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 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 ditierent kinds of hickory, including the shell-bark, the bitter-nut, 

 and the pecan, are extensively damaged by the JScoIytus ■i-spifwsus. 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 decph' 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 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 larvae of 

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

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



