Treehoppers and thorn bugs are members of the family Membracidae, a group of insects related to the cicadas and the leafhoppers. About 3,200 species of treehoppers in over 400 genera are known. They are found on all continents except Antarctica; only five species are known from Europe.

Treehoppers, due to their unusual appearance, have long interested naturalists. They are best known for their enlarged and ornate pronotum, expanded into often fantastic shapes that enhance their camouflage or mimicry, often resembling plant thorns (thus the commonly used name of "thorn bugs" for a number of treehopper species). The specialized pronotum (or helmet) may not be simply an expansion of the prothoracic sclerite, but a fused pair of dorsal appendages of the first thoracic segment. These may be serial homologues of insect wings, which are dorsal appendages of the second and/or third thoracic segments, although this interpretation has been seriously challenged. Evidence for this theory included the development of the helmet, which arises as a pair of appendages attached to each side of the dorsal prothorax by an articulation with muscles and a flexible membrane that allow it to be mobile (also, similar genes are involved in development of the helmet and the wings).

https://en.wikipedia.org/wiki/Treehopper