230 THE XYLOPHAGA. 



injurious^ and tlie slimy larvae of some species of 

 Selandria {S. Cerasi, &c.) often commit serious ravages 

 on our fruit-trees. The larva of Athalia Centifolice 

 feeds upon the leaves of turnips^ to which it has 

 occasionally proved itself a most formidable enemy, 

 causing the complete destruction of the crops over a 

 considerable extent of country. The lar\^a_, from its 

 black colour, is known to farmers in some parts of the 

 country by the name of the " nigger/^ whilst others, 

 perhaps offended by the vulgarity of this title, give it 

 the more refined appellation of the black caterpillar. 

 The perfect insect, like that of the gooseberry grub, 

 is a pretty black and yellow fly, with short antennae 

 a little thickened towards the apex : it is common in 

 the fields during the summer. 



In some curious genera, consisting of small insects, 

 the ovipositor, although found essentially in the same 

 way as in the rest of the tribe, is not concealed within 

 the abdomen, but projects from its extremity in the 

 form of a tail, which is sometimes nearly as long as 

 the abdomen itself. One species, the Cephus pyg- 

 mcBUS, feeds in its larva state in the interior of the 

 stems of the wheat plant, to which it sometimes does 

 great injury; and the larva of a still more curious 

 form, the Xyela pusilla, distinguished by the extra- 

 ordinary length of the third joints of the antennae, is 

 said to live in wood. 



Both in structure and habit therefore, as we shall 

 see, this little insect, which scarcely measures a sixth 

 of an inch in length, leads us directly to the second 

 tribe of the Hymenoptera^ which agrees with the 



