IIL.UIl'TLHA. 



571 



from which they obtain their nourishment ; the two sexes are winged ; the iarvre have the body gene- 

 rally very flat ; the head broad, and the abdomen rounded behind. Their legs are terminated by a 

 menihranous vesicle, accompanied beneath by two ungues. Four broad pieces, which are the sheaths of 

 the wing-covers and wings, distinguish the pupa; : many in this state, as in that of the larva, are 

 covered by a white cottony secretion, arranged in flakes. Their excrements, form threads or masses, of 

 a gummy saccharine nature. 



Some species, by puncturing vegetables to extract the sap, produce in various parts, especially in the flowers and 

 bails, monstrosities, bavin? the appearance of galls. In tins number is PtjfUa Bust, figured by Kdaumur, 

 Mem. Ins., vol. iii. pi. 19, fig. 1—14, which is found on the box. The alder, fig, nettle, &c. produce other 

 species. 



Latreille has formed with the species which lives in the flowers of Juncus articulatus, a genus, under the name 

 of l.hia. The antennae are much thickened at the base. 



[Mr. Curtis has published the figure of another genus under the name of Livilla, founded upon a small, inter- 

 esting British species.] 



The other Aphidii have only six or eight joints in the antennae, the last of which is not terminated 

 by two seta:. 



Sometimes the wing-covers and wings are linear, fringed with hairs, and carried horizontally upon 

 the body, which has nearly a cylindrical form ; the proboscis being small, or scarcely distinct. The tarsi 

 are terminated by a vesicular joint without ungues ; and the antennae have eight somewhat moniliform 

 joints. Such is the genus 



Thrips, Linn.,— 



The species of which are extremely active, and appear to leap rather than fly. When much irritated, 



they elevate and bend the extremity of their bodies into an arch in the same manner as the Staphylini. 



They live upon flowers and plants, and under the hark of trees. The largest species scarcely exceed a 



line in length. 



Latreille observes in a note that the structure of the mouth exhibited to him characters 

 winch appeared essentially to distinguish the species of Thrips from the other insects of 

 this order. M. Strauss also, who had studied them with admirable precision, considered 

 that they belonged to the order Orthoptera. [Subsequently, the genus has been raised 

 to the rank of a distinct order by Mr. llaliday in a valuable memoir published in the En- 

 tomological Magazine, under the name of Thysanoptera, and I have illustrated the structure 

 of the mouth in my Modern Classification of Insects, vol. ii. p. 1, with figures. Mr. 



k. ;i -\~Ti,ri P ». llaliday has established a number of generic and subgeneric divisions.] 



Sometimes the wing-covers and wings are oval or triangular, without a fringe of hairs, and are 



deflezed at the sides like a roof; the rostrum is very distinct ; the tarsi are terminated by two ungues; 



and the antenna; have only six or seven joints : these form the genus 



Aphis, Linn. 



Aphis, proper, has the antennae longer than the thorax, 7-jointed, the third being elongated; the eyes are entire, 

 ami the posterior extremitv 'if 1 in abdomen is furnished with two horns or tubercles. 



They live mostly in society upon trees ami plants, which t li<\ suck with their proboscis. They do not leap, and 

 crawl but slowly. The two horns at the extremity of the body in many species are 

 tubes, from which frequentlj exude small drops of a transparent saccharine fluid, 

 [termed honey-dew], of which the ants are very fond. Bachsociet] consists in spring 

 and slimmer of plant-lice always apterous, and of pupa; [deini-nymphes], of which the 

 wings ought to be developed; all these individuals are females, which produce living 



young, Which are ejected tail foremost, without an\ previous coupling. The mail's, 



amongst which some are winged and some wingless, appear on!) at the end ol the summer or in autumn. They 

 fecundate the last generation produced from the preceding individuals, consisting of wingless females which 

 require impregnation, after which they deposit n'.^ upon the branches of trees, which remain in that state all 

 through the winter, from which young plant-lice are produced in the spring, capable of multiplying without union 

 with the males. 



the influence of a single impregnation thus extends through several successive generations. Bonnet, to whom 

 we arc indebted for the majority of the facts observed upon tins subject, obtained, b) the Isolation of fen. 

 nme generations in the Bpace of three mouths, 'the punctures which the plant-lice make m the leaves ami young 

 twigs of vegetables, often cause these parts to assume different forms, as nur] be seen in the young buds of tht 

 lime, tin' leaves of the jo..s, ■berry, pear, and especially of the elm, poplar, \c. where thej produce a knui of vesi- 

 cles or excrescences, con taininr whole families of plaut-lice, and often u saccbai me fluid, in tin- interior. The 



Fig. MS.— ApMi B 



