Gallische_Feldwespe_Polistes_dominula_4447

The mesothorax is the middle of the three segments of the

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

of hexapods, and bears the second pair of legs. Its principal

sclerite A sclerite (Greek language, Greek , ', meaning "hardness, hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instea ...

s (exoskeletal plates) are the mesonotum (

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

), the mesosternum (

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

), and the mesopleuron (

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

) on each side. The mesothorax is the segment that bears the forewings in all winged insects, though sometimes these may be reduced or modified, as in

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

s (

Coleoptera Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

) or

Dermaptera Earwigs make up the insect order Dermaptera. With about 2,000 species in 12 families, they are one of the smaller insect orders. Earwigs have characteristic cerci, a pair of forceps-like pincers on their abdomen, and membranous wings folde ...

, in which they are sclerotized to form the

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

("wing covers"), and the

Strepsiptera The Strepsiptera () are an order of insects with eleven extant families that include about 600 described species. They are endoparasites of other insects, such as bees, wasps, leafhoppers, Zygentoma, silverfish, and cockroaches. Females of most s ...

, in which they are reduced to form

haltere ''Halteres'' (; singular ''halter'' or ''haltere'') (from , hand-held weights to give an impetus in leaping) are a pair of small club-shaped organs on the body of two orders of flying insects that provide information about body rotations du ...

s that attach to the mesonotum. All adult insects possess legs on the mesothorax. In some groups of insects, the mesonotum is hypertrophied, such as in

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

Hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typi ...

, and

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

), in which the anterior portion of the mesonotum (called the mesoscutum, or simply "scutum") forms most of the dorsal surface of the thorax. In these orders, there is also typically a small sclerite attached to the mesonotum that covers the wing base, called the tegula. In one group of insects, the

Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...

, the dorsal surface of the thorax is typically formed primarily of the prothorax, but also in part by the enlarged posterior portion of the mesonotum, called the scutellum; in the

, the scutellum may or may not be visible, usually as a small triangular plate between the elytral bases, thus similar in position to the

n scutellum. In

and

the mesothoracic scutellum is also distinct, but much smaller than the mesoscutum.

References

Insect anatomy {{insect-anatomy-stub

See also

References