Prothorax

Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on each side.

The prothorax never bears wings in extant insects (except in some cases of atavism), though some fossil groups possessed wing-like projections.

[1] All adult insects possess legs on the prothorax, though in a few groups (e.g., the butterfly family Nymphalidae) the forelegs are greatly reduced.

In most treehoppers (family Membracidae, order Hemiptera), the pronotum is expanded into often fantastic shapes that enhance their camouflage or mimicry.

Similarly, in the Tetrigidae, the pronotum is extended backward to cover the flight wings, supplanting the function of the tegmina.