HYMENOPTERA. 391 



pieces of the sheath. The borer often pierces the bark and 

 wood to the depth of half an inch or more, and is sometimes 

 driven in so tightly that the insect cannot draw it out again, but 

 remains fastened to the tree till she dies. The eggs are oblong 

 oval, pointed at each end, and rather less than one twentieth of 

 an inch in length. The larva, or grub, is yellowish white, of a 

 cylindrical shape, rounded behind, with a conical, horny point on 

 the upper part of the hinder extremity, and it grows to the length 

 of about an inch and a half. It is often destroyed by the mag- 

 gots of two kinds of ichneumon-flies (Pimjjla atrata and lunator 

 of Fabricius). These flies may frequently be seen thrusting 

 their slender borers, measuring from three to four inches in length, 

 into the trunks of trees inhabited by the grubs of the Tremex 

 and by other wood-eating insects ; and, like the female Tremex, 

 they sometimes become fastened to the trees, and die without be- 

 ing able to draw their borers out again. 



Urocerus albicomis, of Fabricius, the white-horned Urocerus, 

 has white antenna?, longer and more tapering than those of the 

 pigeon Tremex, and black at each end. The female is of a deep 

 blue-black color, with an oval, white spot behind each eye, and 

 another on each side of the hinder part of the abdomen. The 

 horn on the tail is long, and shaped like the head of a lance. 

 The wings are smoky brown, and semitransparent. The legs 

 are black, with white joints. The body measures about an inch 

 in length, and the wings expand nearly two inches. The male has 

 a black head, with a white spot, on each side, behind the eyes. 

 His thorax and legs are black. His abdomen is flattened, and 

 rust-colored, and ends with a flattened horny point. He meas- 

 ures about an inch in length. This species, which is not com- 

 mon, has been found on pine-trees in July. 



Urocerus nitidus, the polished horn-tail, is an undescribed spe- 

 cies, for which I am indebted to the Rev. L. W. Leonard. 

 The male is not known to me. The female is of a deep blue 

 color, downy on the head and thorax, smooth and highly polished 

 on the abdomen, the end of which is armed with a flattened horny 

 point. Her wings are clear and perfectly transparent, with brown- 

 ish veins, and have only a faint smoky tinge towards the tip. Her 

 legs are ochre-yellow. The body of this insect measures rather 



