 They tend to be lively and capable of active leaping and flight.The immature instars of some species camouflage themselves extremely effectively by gluing sand grains and similar particles to their backs, and so do the adults of a few species.They are not conspicuous and most species are physically small and occur patchily and in small numbers; these factors make them difficult to study and partly explain why there is a poverty of detailed knowledge of the biology of most species.