228 



HYMENOPTEKA. 



The genus Tremex is known by the wings liaving two mar- 

 ginal and three snbmarginal cells. Tremex Columba Linn, in- 

 fests the elm, pear and button-wood. The female is an inch 

 and a half long, rust-red, varied with black, while the abdomen 

 is black with seven ochre-yellow bands on the upper side, all 

 but the two basal ones being interrupted in the middle. They 

 fly during the last of summer. 



"Dr. Harris thus describes the habits of this interesting in- 

 sect. The female, when about to laj- her eggs, draws her borer 

 out of its sheath, till it stands perpendicularly under the middle 

 of her body, when she plunges it, b}' repeated wiggling 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 tightl}^ that the insect cannot 

 draw it out again, but remains fast- 

 ened 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 extremitj', 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 

 (Rhyssa 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-eat- 

 ing insects ; and like the female of the Tremex they some- 

 times become fastened to the trees, and die without being able 

 to draw their borers out again." 



We have noticed the trunk of an elm, at Saratoga Springs, 

 perforated by great numbers of holes, apparently made by these 

 insects. T. latitarsus Cresson (Fig. lo-l ; a, antenna ; &, wing ; 

 c, hind leg) is remarkable for the expansions on the hind legs. 

 It lives in Cuba. 



Fig. 154. 



