HYMEXOPTERA. 427 



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 exti-cmity, and it grows to the lengtli 

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

 maggots of two kinds of ichneumon-flies {Pimpla 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 being able to draw their borers out 

 again. 



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

 has white antennae, 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 abdo- 

 men. 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 measures about an inch in length. 

 This species, which is not common, has been found on pine- 

 trees in July. 



Urocerus nUidiis, the polished horn-tail, is an undescribed 

 species, 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 pol- 

 ished on the abdomen, the end of which is armed with a 

 flattened horny point. Her wings are clear and perfectly 

 transparent, with brownish veins, and have only a faint smoky 

 tinge towards the tip. Her legs are ochre-yellow. The body 

 of this insect measures rather more than three quarters of an 

 inch, exclusive of the horn on the tail. This insect differs 

 from the European Urocerus Juvcncus in the much greater 



