538 
HYMENOPTERA. 
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, wdien she 
plunges it, by repeated wriggling motions, through the bark 
into the wood. When the hole is made deep enough, she 
then droi)s 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. 
Uroceriis alhicornis^ of Fabricius, the white-horned Uro- 
cerus, has Avliite 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 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. 
