The thorax is the midsection (tagma) of the hexapod body (insects and entognathans).
It is formed by the prothorax, mesothorax and metathorax and comprises the scutellum; the cervix, a membrane that separates the head from the thorax; and the pleuron, a lateral sclerite of the thorax.
In dragonflies and damselflies, the mesothorax and metathorax are fused together to form the synthorax.
[1][2] In some insect pupae, like the mosquitoes', the head and thorax can be fused in a cephalothorax.
Members of suborder Apocrita (wasps, ants and bees) in the order Hymenoptera have the first segment of the abdomen fused with the thorax, which is called the propodeum.