The orthopteran family Rhaphidophoridae of the suborder Ensifera has a worldwide distribution. Common names for these insects include cave crickets, camel crickets, spider crickets (sometimes shortened to "criders" or "sprickets"), and sand treaders. Those occurring in New Zealand are typically referred to as jumping or cave wētā. Most are found in forest environments or within caves, animal burrows, cellars, under stones, or in wood or similar environments. All species are flightless and nocturnal, usually with long antennae and legs. More than 500 species of Rhaphidophoridae are described. The well-known field crickets are from a different superfamily (Grylloidea) and only look vaguely similar, while members of the family Tettigoniidae may look superficially similar in body form.

Description

Most cave crickets have very large hind legs with "drumstick-shaped" femora and equally long, thin tibiae, and long, slender antennae. The antennae arise closely and next to each other on the head. They are brownish in color and rather humpbacked in appearance, always wingless, and up to 5 cm long in body and 10 cm for the legs. The bodies of early instars may appear translucent. As their name suggests, cave crickets are commonly found in caves or old mines. Some inhabit other cool, damp environments such as rotten logs, stumps and hollow trees, and under damp leaves, stones, boards, and logs. Occasionally, they prove to be a nuisance in the basements of homes in suburban areas, drains, sewers, wells, and firewood stacks. Some reach into alpine areas and live close to permanent ice, such as the Mount Cook "flea" (Pharmacus montanus) and its relatives in New Zealand.

Subfamilies and genera

Aemodogryllinae

Genera include:

Anoplophilinae

Genera include:

Ceuthophilinae

cave crickets, camel crickets and sand treaders: North America Genera include:

Dolichopodainae

cave crickets: southern Europe, western Asia

Gammarotettiginae

Auth. Karny, 1937 – North America

Macropathinae

Gondwanan cave crickets Genera include:

† Protroglophilinae

Rhaphidophorinae

Genera include:

Troglophilinae

cave crickets: the Mediterranean region

Tropidischiinae

camel crickets: Canada An as-yet-unnamed genus was discovered within a cave in Grand Canyon–Parashant National Monument, on the Utah/Arizona border, in 2005. Its most distinctive characteristic is that it has functional grasping cerci on its posterior.

Ecology

Their distinctive limbs and antennae serve a double purpose. Typically living in a lightless environment, or active at night, they rely heavily on their sense of touch, which is limited by reach. While they have been known to take up residence in the basements of buildings, many cave crickets live out their entire lives deep inside caves. In those habitats, they sometimes face long spans of time with insufficient access to nutrients. Given their limited vision, cave crickets often jump to avoid predation. Those species of Rhaphidophoridae that have been studied are primarily scavengers, eating plant, animal, and fungi material. Although they look intimidating, they are completely harmless. The group known as "sand treaders" is restricted to sand dunes, and are adapted to live in this environment. They are active only at night, and spend the day burrowed into the sand to minimize water loss. In the large sand dunes of California and Utah, they serve as food for scorpions and at least one specialized bird, LeConte's thrasher (Toxostoma lecontei). The thrasher roams the dunes looking for the tell-tale debris of the diurnal hiding place and excavates the sand treaders (the range of bird is in the Mojave and Colorado Deserts in the U.S.).

Interactions with humans

Cave and camel crickets are of little economic importance except as a nuisance in buildings and homes, especially basements. They are usually "accidental invaders" that wander in from adjacent areas. They may reproduce indoors, and are seen in dark, moist conditions such as a basement, shower, or laundry area, as well as in organic debris (e.g., compost heaps) that serve as food. They are fairly common invaders of homes in Hokkaido and other chilly regions in Japan. They are called kamado-uma or colloquially benjo korogi (便所コオロギ, literally, "toilet cricket"). A representation of a female from the Troglophilus genus has been found engraved on a bison bone in the Cave of the Trois-Frères, showing that they were likely already present around humans, maybe as pets or pests, in caves inhabited by prehistoric populations in the Magdalenian.