OCR Text |
Show 84 INSECTA. This family is composed of two tribes. Lat vulgarly In the first, that of the TENTH~EDINET~~erve.,elongated termed Mouches-a-scie, or Saw-jlzes, we 0f d' 'tated ligula; and compressed man dI'b l es•' a t •· fid or sort o tgt . tl • ted blades, umted an ovipositor formed of two serrated, pom The maxillary . mder the anus. and lodged In a groove t. • . d the labials of four ; . }} d of SIX JOIOtS, an d' palp1 are a compose The wings are always 1- the latter are always the shortehs.t. 'b forms the genus vided into numerous cells. T IS trt e TENTHREDO, Lin. Insects which is rounded poste· The cylindrical abdomen of th.ese d 1 sely J'oined to the thorax d f . nnuh an so co . riorly, compose o nme a . ~us· the ragged appearance of thetr that the two seem to be contmu ' 1 ncl usually coloured bodies rttl oundcd granu ar, a wings; the t~o I e r ' ether with their heavy port, cause situated behmd the scutellum, tog P d composition of the an· . · ed The 1otm an them to be eastly recogmz · t ncl dentated. The ex- Tl · mandibles at·e s rong a tennre vary. 1eu· branous or less coriaceous . f h · x'llre is almost mem ' tremtty o t eir rna, I . I i are filiform or nearly setaceous, and than their stem. 1 heir pa ~ 1 . t ·aight rounded, and divided f . . "nts The hgu a Is s I ' consist o SIX J01 • • the intermediate of which is the nar-into thr~e doubled i~:st~~~t' short, and its palpi, shorter than the row~st; .Its sheat!l f fou/. oints, the last almost bordering on an maxtllartes, a~::s;;no of the f~male presents at its inferior extr~mity oval. biT he ble squamous ovipositor that is serrated, pomted, a dou e, mova ' . £ · · t sheath or and lodged between two concave lammre, ormmg 1 s ca~~· is by the alternate action of the teeth of this ovipositor, tha~ the Insect rna k es anum ber of little holes in the .b ran. ches, adn d va·r tOus t f trees and plants, in each of which lt first eposlts ~n other par s 0 • h · · med 1s and then a foaming liquid, the use of wluc ' lt lS presu . ' . e!g'revent the aperture f;om closing. Th~ woun~s ni~de m thls tw apy b ecome m ore and more convex by the mcreasmg fs 1ze o11f tuhte e • Sometimes these excrescences assume the ~orm o ~ ga -n ' eft~er ligneous or soft and pulpy, or resemble a httle fruit, accord· ing to the nature of the parts of the plant that are affect~d b~ the~~ These tumours then form the domicil of the larvre which ~nha them either solitari. ly or m· soci· ety. Th ere th ~ y undergo th. eir medte· hosis and issue from them through a Circular openmg ~a ainm tohrepi r par'i etes by the teeth of the I nsect. G eneral ly speakmg, HYMENOPTERA. 85 however, these Iarvre live exposed on the leaves of the trees and plants on which they feed. In the general form of the body, its colours, the exterior disposition of its dermis, and in the great numbet· of feet these larvre closely resemble caterpillars, and have been called false, or pseudo-caterpillars: but they are distinguished from the latter by having from eighteen to twenty-two feet, the number of these organs in the caterpillar being rrom ten to sixteen. Several of these pseudo-caterpillars t'oll themselves up spirally; in others the posterior portion of the body is arched. In order to become nymphs they spin a cocoon, either in the eartlo!, or on the plants where they have lived. There they pass several consecutive months, or even the \Yhole winter, in their first state, and only pass into that of a nymph a few days previous to the one in which they appear as perfect Insects or Saw-flies. M. Dutrochet, corresponding member of the Academie des Sciences, has published some observations on the alimentary canal of these Insects in the Journal Physique. In some, where the antennre in several consist of but nine joints, and where the internal extremity of the two anterior tibire is furnished with two straight and divergent spines, the ovipositor does not project posteriorly. Here the labrum is always apparent, and the middle of the inner side of the four posterior tibire is destitute of spines, or presents but one. The 1arvre or pseudo-caterpillars have from twelve to sixteen membranous feet. The antennre, always short, sometimes terminate either in a thick inflation in the form of a reversed cone rounded at the extremity, or of a button, or in a large joint forming an elongated, prismatic or cylindrical club forked in some males; the number of the preceding joints is five at most. Those species, in which these organs, simil!lr in both sexes, are terminated by a globuliform inflation, or by one resembling a reversed cone rounded at the extremity( 1 ), and preceded by from four to five joint~, and where the two nervures of the superior wings forming the rib, as far as the callous point, are contiguous, or closely approximated and parallel, without a wide intermediate sulcus, form the genus (1) This inflation is formed by the fifth or sixth joint, but which, in several, presents vestiges of two or three annulal' divisioas. |