Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/164

 152 INSECT which live in the nests of spiders (and also tree wasps), and in Mantispa undergo a kind of hypermetamorphosis ; the Ncmo- 2)teridse, with their linear posterior wings ; the Ant-Lions, with their clavate antennae and trap-forming larva; ; the Chrysopidss and Hcmcrobiidse, known to feed on aphides in their larval stage, the former often emitting a disgusting odour ; and the very curi ous little Coniopterygidse, covered with a whitish waxy secretion, and diil ering from all others in the extremely simple neuration, In Osmylus and Sisyra the larvae are aquatic; and those of the latter have been found in the interior of the freshwater sponge. ORTIIOPTERA. Typically with four densely reticulate unequal wings (or apterous), whereof the anterior are more or less coriaceous, the posterior folded under them, and membranous ; in the most typical groups they are defiexed, and closely applied to the body longitudinally in repose. Mouth mandibulate. Metamorphosis incomplete. Having adopted metamorphosis as a basis for classifica tion, it became necessary to view this order after the manner universal amongst German systematists, and to include in it many groups that are ordinarily accepted as neuropterous, the only plan possible without the erection of independent orders for their accommodation. The result is that more absolute homogeneity from a general point of view is attained, and we have to deal with an order made up of otherwise most incongruous elements, but somewhat relieved by the sharpness with which the great groups are defined. Regarding the two great divisions, Pseudo-Neiiroptera and Orthoptera genuina, as a whole, the main distinction really consists in the fact that in the former the four wings are equally membranous, whereas in the latter the anterior pair are more or less coriaceous ; another difference is in the head, which in the former is horizontal, whereas in the latter it may be described as vertical ; but this distinction only applies to the typical groups. Thus there is really little more difference than exists between the two great divisions of Hemiptera, now almost universally placed in one order. Naturally allowing the Pseudo-Neuroptera the first place as following on from the true Neuroptera (though some would say the Dragon-ilies are really the typical Neuroptera of Linnaeus), these must be first considered. Adopting the descending scale, the main groups may be glanced at as follows: The Odonata (Dragon-flies ; constituted an order by Fabricius) may be considered the most highly organized, with regard to theii powerfully mandibulate mouth, strong, densely reticulate wings, &c. The special peculiarities of this group (including the extra ordinary structure of the mouth in the preparatory stages, and the anomalous position of the genital organs in the male) have been fully discussed in the article DRAGON-FLY (q.v.). The Ephemeridx (see EPHKMEBIDJE) follow. After these come the Perlidas, aquatic insects in their preparatory conditions, remarkable for the comparatively weak development of the mouth parts (shared with the Ephemeridse) in the perfect state, the four wings longitudinally horizontal and overlapping, the stout quadrate or oblong prothorax, the frequent presence of two articu lated tails, the long setaceous antenna 1, kc. This group is also re markable as being the first in which the persistence of external branchiae in the imago was detected (a peculiarity since found to be of frequent occurrence in them, and extending to other orders). They are known familiarly as Stone-Flies, and form a large portion of the stock-in-trade of an angler. The Einbidas constitute a very small group, which in general form much resemble I crlidse, but have, on the other hand, affinities with the white ants. The larvae live habitually under stones in little galleries, and a recent discovery appears to prove that they feed on roots. Termitidse, (or White Ants, placed by some authors in the true Orthoptera) are social insects living in immense communities, and forming nests on the ground or on trees. In some respects there is analogy between these and social Hymcnoptcra, and the diversity of condition in a single species is even greater. Winged forms of both male and female exist (the wings being shed at a certain time), and there are also commonly apterous forms known as workers and soldiers, whose ollice it is to build the dwellings and protect the inmates, the soldiers having the head provided with a powerful horn or elongated mandibles. Each condition has its own special immature form, so that it is probable no more specially polymorphic insects exist. The wings are carried horizontally and overlapping in repose ; the prothorax is well developed, and tl tarsi are four-jointed. Recent observations tend to show that speci ally prepared food (comminuted wood) is provided for the larva*. Psucidie are a small group of small insects remarkable for their swollen face, setiform antenna-, narrow prothorax, and large meso- thorax, four-jointed maxillary palpi, and rudimentary labial palpi, two- or three-jointed tarsi. The wings are defiexed (often absent), with ordinarily very open neuration. These insects live on fungi and debris and also occasionally on dry animal substances, as in the case of the Book-Louse, ordinarily so abundant in neglected collections of insects, and erroneously supposed to occasion a ticking like that ofAnobium. There remain two groups the position of which has occasioned much controversy, but which are now often placed here, not, per haps, because the affinities are very marked, but more to accommo date them with a resting-place in a division of Insccia the characters of which are so very elastic. The first of these are the Thysanqptera, considered a distinct order by Haliday, the founder of the name, and by Burmeister placed in his order Gymnognatha as a distinct group termed Physopoda ; by some authors they are placed in the Hemiptera. It is true that the mouth forms a short rostrum with only bristle-like mandibles, but the presence of distinct palpi would appear definitely to invalidate the position in Hemiptera. The wings arc four in number, lying horizontally on the back and crossing at the tips ; they are very slender, membranous, without ncrvures or nearly so, and strongly ciliated, or they may be wanting in some species, even in the perfect state. These insects are familiarly known as T/irifis, and sometimes occasion nruch damage to various kinds of plants by sucking the juices, which the almost haustellate nature of the mouth enables them to do. They are mostly very minute insects, and have been divided into many sections and genera on structural characters. The second of the above-mentioned groups is the Mallophaga (or Bird-Lice), which it is convenient to separate from the Aiwplura (or true Lice) on account of the structure of the mouth, which is man dibulate and also carries palpi. On account of the absence of meta morphoses, some place them (with the Anoplura) as outside the pale of the Tnsccta, but they may be regarded as degraded Pscndo-Ncuro- ptera. They for the most part live on the feathers of birds (each bird having its particular parasites), but a few also on mammals. What may be termed Orthoptera genuina consist of groups for the most part very sharply defined. The Blattidse (or Cockroaches) form the order Dictyoptera of Leach. These are insects of flattened form, with four horizontal wings (or apterous), of which the anterior pair are considerably cori aceous, but with distinct neuration ; the head small ; tarsi five- jointed. The eggs are not laid separately, but are contained in a common capsule which is carried about by the female at the extremity of her abdomen. There are many genera and species, of which latter the abundant Pcriplaneta oricutalis is the most familiar. Forficulidss (or Earwigs) form the order Euplexqptera of West- wood and the group Dermatqptera of Burmeister. Externally they much resemble Goleoptera of the family Staphylinidse in form (but with pinccr-like appendages at the extremity of the abdomen), the anterior wings being abbreviated and coriaceous, separated by a suture, and concealing the ample but folded posterior wings (but some forms are apterous) ; the tarsi three-jointed. The eggs are deposited in cavities in the earth, and are guarded (at any rate in some) by the mother. Mantidae are mostly large elongate insects with strongly de veloped raptorial anterior legs (hence the insects are carnivorous). The prothorax very long; tarsi five-jointed ; wings often ample 01 frequently wanting, all reticulate, but the anterior pair slightly more coriaceous. The earlier states greatly resemble the perfect insect without wings. The eggs are contained in a kind of case formed of a secretion voided with them, in which they are arranged in rows, the whole mass being attached to twigs, &c. FhasmidzK (Spectres, or Walking-Sticks) have considerable exter nal resemblance to the former, but the anterior legs are not rapto rial, and the insects are phytophagous. The wings (when present) are usually much shorter than the abdomen. Most of the species mimic (as do those of the last family) leaves or twigs, often to such a degree that it is hard to imagine one is regarding an insect. Oryllidsei form the first of a division termed Saltatoria (as opposed to Cursoriaor Grcssoria), from the structure of the hind legs fitting them for jumping. The antenna; are long and setaceous ; tarsi three-jointed ; anterior wings lying horizontally over the folded posterior. The males mostly produce sound by a special structure at the base of each anterior wing acting on the posterior. This family is mi- le up of materials presenting considerable diversity, but may be grouped roughly in two, according as the anterior legs are formed for digging (Mole-Crickets) or for running (Crickets). Locustidee have the antenna; very long and slender; the tarsi four- jointed ; the anterior wings longitudinally defiexed. The female ordinarily has a broad curved ovipositor suitable for forming