HEMIPTERA. 433 



rostrum is very small or but little distinct. The tarsi are terminated 

 by a vesicular joint without hooks. The antennae consist of eight 

 graniforrn joints. Such are the Insects which form the genus 



THRIPS, Lin. 



They are extremely agile, and seem to leap rather than fly. When we irri- 

 tate them beyond a certain point, they turn up the posterior extremity of 

 their body in the manner of the Staphylini. They live on flowers, plants, 

 and under the bark of trees. The largest species scarcely exceed one line 

 in length. 



Sometimes the elytra and wings, oval or triangular, and without 

 a fringe of hairs along the margin, are inclined or tectiform. The 

 rostrum is very distinct. The tarsi are terminated by two hooks, 

 and the antennae have but six or seven joints. Such is the genus, 



APHIS, Lin. 



In Aphis properly so called, the antennae are longer than the thorax, and con- 

 sist of seven joints, the third of which is elongated; the eyes are entire, 

 and there are two horns or mammillae at the posterior extremity of the ab- 

 domen. 



Almost all Aphides live in society on trees and plants, of which they 

 suck the juices with their trunk. The two horns observed at the posterior 

 extremity of the abdomen in a great number of species are hollow tubes 

 from which little globules of a transparent, honey-like fluid frequently ex- 

 ude, on which the Ant eagerly feeds. 



The wounds inflicted on the leaves or tender twigs of plants, by Aphides, 

 cause those parts of the vegetable to assume a variety of forms, as may be 

 observed on the shoots of the Lime tree, the leaves of Gooseberry bushes, 

 Apple trees, and particularly those of the Elm, Poplar and Pistachio, in which 

 they produce vesicles or excrescences enclosing colonies of Aphides, and 

 frequently an abundant saccharine fluid. Most of these Insects are covered 

 with a farinaceous substance, or cotton-like filaments, sometimes arranged 

 in bundles. The larva of the Hemerobii, those of several Diptera, and of 

 Coccinellse, destroy immense numbers of Aphides. 



A. quercus, L. Brown; remarkable for its rostrum, which is at least 

 thrice as long as the body. 



.5. fagi, L, Completely covered with white down resembling cotton. 



3 E 



