HEJnPTERA. 18l 



Here the antennae are composed of from ten to eleven joints, the 

 last of Avhich is terminated by two setae. 



They possess the faculty of leaping, and form the genus 



PsYLLA, Geoff. — Chermes, Lin. 



These Hemiptcra, also called pseudo-aphides, or faux-pucerons, live 

 on the trees and plants from which they derive their nourishment ; 

 both sexes are furnished with wings. Their larvae usually have a 

 very flat body, broad head, and the abdomen rounded posteriorly. 

 Their legs are terminated by a little membranous vesicle accom- 

 panied beneath with two hooks. Four wide and flat pieces, which 

 are the sheaths of the elytra and wings, distinguish the nymph. 

 Several in this state, as well as in the first, are covered with a white 

 substance resembling cotton, arranged in flakes. Their fyeces form 

 threads or masses, of a gummy and saccharine nature. 



Some species, by wounding plants in order to suck their juices, 

 produce excrescences somewhat resembling gall-nuts, particularly on 

 their leaves or buds. Of this number is the 



P. buxi ; Chermes buxi, L. ; Reaum., Mem., Insect., Ill, xix, 

 1,14. Green, with brown-yellowish wings. 



Other species are also found on the Alder, Fig tree. Nettle, &c.* 

 A species which lives in the flowers of the rushes has been 

 erected into a genus by Latreille. under the name of Livia.. The an- 

 tennee are much thicker inferiorly than at their extremity [. 



The remaining Aphidii have but six or eight joints in the an- 

 tennre ; the last is not terminated by two setee. 



Sometimes the elytra and wings are linear, fringed -with hairs, and 

 extended horizontally on the body, wliich is almost cjdindrical ; the 

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

 by a vesicular joint Avithout hooks. The antennse consist of eight 

 graniform joints. Such are the Insects which form the genus 



Thrips, Lhf. 



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

 we irritate them beyond a certain point they turn up the posterior ex- 

 tremity of their body in the manner of the Staphylini. They live on 

 floAvers, plants, and under the 1)ark of trees. The largest species 

 scarcely exceed one line in length J. 



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

 fringe of hairs along the margin, are inclined ortectiform. The ros- 



* See Fab., Geoff., De Geer. 



t Lat., Gen. Crust, et Insect., Ill, p. 170; Arh., Faun. Insect., VI, 21. 



X See Lat., Ibid. p. ead. and the authors already quoted. In the organization of 

 the mouth, I have detected characters which seem to distinguisli it essentially from 

 that of Insects of this order. M. Straus, who has studied it with admirable minute- 

 ness, thinks that Thirps belong to the order of the Orthoptera. 



