Hydropsychids are capable of performing a defensive stridulation in their larval stages. Many insects generate sound by mechanical rubbing of body structures, a mechanism known as stridulation. Some species startle an attacker by producing sounds through a process known as stridulation. Males attract females by singing "via" stridulation. Common onomatopoeic words for the sounds produced by stridulation include chirp and chirrup. The organ of the stridulation of the males is generally brown. This mechanism is the avian equivalent of arthropod stridulation. First the stridulation of the males attracts females. The bird vibrates loudly via stridulation of rectrice quills. In some species, females are also capable of stridulation. In male grasshoppers of the family Pneumoridae, the enlarged abdomen amplifies stridulation. Their stridulation plays a role in interspecific defense mechanisms. Initially, crickets were kept for their "songs" (stridulation). They have combs in their legs which they use for communication (stridulation) with other larvae. In grasshoppers and crickets, this is achieved by stridulation.