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The number of segments in an antenna varies amongst insects, with higher flies having 3-6 segments, [21] while adult cockroaches can have over 140. [22] The general shape of the antennae is also quite variable, but the first segment (the one attached to the head) is always called the scape, and the second segment is called the pedicel.
The thoracic segments have one ganglion on each side, which are connected into a pair, one pair per segment. This arrangement is also seen in the abdomen but only in the first eight segments. Many species of insects have reduced numbers of ganglia due to fusion or reduction. [8]
This glossary of entomology describes terms used in the formal study of insect species by entomologists.. When present, elytra of the Staphylinidae are markedly abbreviate. This fly in the genus Scaptomyza has clearly visible rows of para-sagittal acrostichal bristles on its thorax the alitrunk of aculeate Hymenoptera comprises the three thoracic segments, plus the propodeum, which strictly ...
In hymenopterans of the suborder Apocrita (wasps, bees and ants), the mesosoma consists of the three thoracic segments and the first abdominal segment (the propodeum). For historical reasons, in ants it is commonly referred to by the alternative name alitrunk. [1] [2] [3]
Two thoracic segments are fused into the head; one thoracic segment is in the posterior tagma. Other kinds of copepod also have two tagmata but formed by different segments. The development of distinct tagmata is believed to be a feature of the evolution of segmented animals, especially arthropods. In the ancestral arthropod, the body was made ...
Abdominal segments three through six and ten may each bear a pair of legs that are more fleshy. [21] The thoracic legs are known as true legs and the abdominal legs are called prolegs. [64] The true legs vary little in the Lepidoptera except for reduction in certain leaf-miners and elongation in the family Notodontidae.
Insects have spiracles on their exoskeletons to allow air to enter the trachea. [1] [page needed] In insects, the tracheal tubes primarily deliver oxygen directly into the insects' tissues. The spiracles can be opened and closed in an efficient manner to reduce water loss. This is done by contracting closer muscles surrounding the spiracle.
All adult insects possess legs on the mesothorax. In some groups of insects, the mesonotum is hypertrophied, such as in Diptera , Hymenoptera , and Lepidoptera ), in which the anterior portion of the mesonotum (called the mesoscutum , or simply "scutum") forms most of the dorsal surface of the thorax.