Turning to the thorax we find that the first segment (prothorax) is distinct and free, with a wide dorsal sclerite.
The abdomen is oval, sandy-grey in hue and beset with warts and bristles; the prothorax forms a mobile neck for the large square head, which carries a pair of long and powerful toothed mandibles.
The prothorax is large and "free," i.e.
The tergite of the prothorax (pronotum) is prominent in all beetles, reaching back to the bases of the elytra and forming a substantial shield for the front part of the body.
The file may be on the head - either upper or lower surface - and the scraper formed by the front edge of the prothorax, as in various wood-boring beetles (Anobium and Scolytus).
Or ridged areas on the sides of the prothorax may be scraped by "files" on the front thighs, as in some ground-beetles.
The well-known "fire-flies" of the tropics are large click-beetles (Elateridae), that emit light from paired spots on the prothorax and from the base of the ventral abdominal region.
Mandibles being well adapted for the capture of small insect-victims. The larvae are more specialized than those of other Adephaga, the head and prothorax being very large and broad, the succeeding segments slender and incompletely chitinized.
The prothorax is convex in front, and is usually drawn out behind into a prominent process on either side, while the elytra are elongate and tapering.
The males are very small, free-flying insects with the prothorax, mesothorax and elytra greatly reduced, the latter appearing as little, twisted strips, while the metathorax is relatively large, with its wings broad and capable of longitudinal folding.
In this family there is often a marked divergence between the sexes; the terminal antennal segments are larger in the male than in the female, and the males may carry large spinous processes on the head or prothorax, or both.
Most of the Chrysomelidae are metallic in colour and convex in form; in some the head is concealed beneath the prothorax, and the so-called "tortoise" beetles (Cassidinae) have the elytra raised into a prominent median ridge.
The larvae have soft, fleshy bodies, with the head and prothorax large and broad, and the legs very much reduced.
3, d), which is large and conspicuous in those insects, such as cockroaches, bugs (Heteroptera) and beetles, which have the prothorax free - i.e.
Readily movable on the segment (mesothorax) immediately behind - smaller and of less importance where the prothorax is fixed to the mesothorax, as in bees and flies.
Prothorax: h, Post-scutellum.
Paired erectile plates (patagia) are borne on the prothorax in moths, while in moths, sawflies, wasps, bees and other insects there are small plates (tegulae) - see Fig.
B, spiracle on prothorax; c, protruded head region; d, tail-end with functional spiracles; e, f, head region with mouth hooks protruded; g, hooks retracted; h, eggs.
But the pupa hangs from the surface by means of paired respiratory trumpets on the prothorax, the dorsal thoracic surface, where the cuticle splits to allow the emergence of the fly, being thus directed towards the upper air.
Prothorax large and free.
Prothorax large and free.
Mandibles present in pupa, vestigial in imago; maxillae suctorial without specialization; first maxillae with lacinia, galea and palp. Prothorax small.
Prothorax small, intimately united to mesothorax.
Prothorax small, and united to mesothorax.
A remarkable fossil from the Scottish Coal-measures (Lithomantis) had apparently small wing-like structures on the prothorax, and in allied genera small veined outgrowths - like tracheal gills - occurred on the abdominal segments.
There are three distinct and large thoracic segments, whereof the prothorax is narrower than the others; the legs are much shorter and stouter than in the winged insect, with monomerous tarsi terminated by a single claw.
In the thorax the pronotum and prosternum are closely associated with the mesothorax, but the pleura of the prothorax are usually shifted far forwards, so that the forelegs are inserted just behind the head.
This section includes a number of families characterized by the backward extension of the prothorax to the tegulae and distinguished from the ants by the absence of " nodes " at the base of the abdomen.
- Head and Prothorax of Cicad from side.
The prothorax (figs.
2.--Head and Prothorax of Cicad, parts separated.
V., Prothorax, b, haunch; a, trochanter.
The Embiidae are feeble, somewhat soft-skinned insects with the prothorax small and the mesothorax and metathorax elongate.
They are relatively shorter and broader insects than the Embiidae with large prothorax and long wings, which have a transverse line of weakness at the base and are usually shed after the nuptial flight.
The prothorax is very small.
Hagen observed that some genera possess wing-like outgrowths on the prothorax, comparable to those seen in certain insects of the Carboniferous Period.
Structurally the Neuroptera are distinguished by elongate feelers, a large, free prothorax, a labium with the inner lobes of the second maxillae fused together to form a median ligula, membranous, net-veined wings without hairy covering, those of the two pairs being usually alike, the absence of abdominal cerci, and the presence of six or eight Malpighian tubes.
The Raphidiidae or snake-flies (q.v.) are remarkable for the long, narrow, tapering prothorax which gives the appearance of a constricted neck, while the female has a long ovipositor.
They may be distinguished from the Neuroptera by the elongation of the head into a beak, the small prothorax, the narrow, elongate wings with predominantly longitudinal neuration, the presence of abdominal cerci and the cruciform larva.
The prothorax is short and the mesothorax very long, the three pairs of legs closely similar, the wings often highly modified or absent, and the cerci short and unjointed.
In this tribe are included Orthoptera with a large prothorax, whose eggs are enclosed in a common purse or capsule formed by the hardening of a maternal secretion.
The Mantidae or " praying insects " have the prothorax elongate and the forelegs powerful and raptorial, while the large, broad head is prominent.
They are readily distinguished by the somewhat rounded prothorax beneath which the head is usually concealed, while the forelegs are unmodified.
But in one family (Sminthuridae) a spiracle, opening on either side between the head and the prothorax, leads to a branching system of air-tubes.
In the Entomobryidae the body is elongate and clearly segmented, but the dorsal region (tergum) of the prothorax is much reduced and the head downwardly directed; the spring is well developed.
In the Achorutidae the head is forwardly directed, the tergum of the prothorax conspicuous, and the spring small or vestigial.