538 HYMENOPTEEA. 



them in the same way. The female, when about to lay 

 her eggs, draws her borer out of its sheath, till it stands 

 perpendicularly under the middle of her body, when she 

 plunges it, by repeated wriggling motions, through the bark 

 into the wood. When the hole is made deep enough, she 

 then drops an egg therein, conducting it to the place by 

 means of the two furrowed 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 maggots of two kinds of ichneumon-flies 

 (Pimpla atrata and lunator (Fig. 251) 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 alhicornis, of Fabricius, the white-horned Uro- 

 cerus, has white antennae, longer and more tapermg 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, witli 

 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. 



