Rhaphidophoridae

Walker, 1869

cave crickets, camel crickets, spider crickets, cave wētā, sand treaders, sprickets

Subfamily Guides

5

is a globally distributed of wingless orthopterans comprising over 500 described . Commonly called cave crickets, camel crickets, or spider crickets, these insects are characterized by elongated , enlarged hind legs adapted for jumping, and a humpbacked body profile. They occupy diverse including caves, forests, animal burrows, and human structures. All species are flightless and , relying heavily on tactile and chemical sensory structures for navigation in dark environments. The family includes notable such as Ceuthophilinae in North America, Macropathinae in the Southern Hemisphere, and Aemodogryllinae in Asia.

Utabaenetes by (c) Steve Young, some rights reserved (CC BY), uploaded by Steve Young. Used under a CC-BY license.Diestrammena by (c) raibums, some rights reserved (CC BY), uploaded by raibums. Used under a CC-BY license.Aemodogryllinae by (c) Kim, Hyun-tae, some rights reserved (CC BY), uploaded by Kim, Hyun-tae. Used under a CC-BY license.

Pronunciation

How to pronounce Rhaphidophoridae: /ræfɪˈdɒfəraɪdiː/

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Identification

Distinguished from true crickets (Gryllidae) by complete absence of wings and inability to produce sound. Separated from katydids (Tettigoniidae) by humpbacked rather than flattened body profile, wingless condition, and arising closely adjacent rather than more separated on the . Distinguished from grasshoppers (Acrididae) by long antennae and lack of wings. Jerusalem crickets (Stenopelmatidae/Anostostomatidae) are more robust with shorter legs and antennae relative to body size. Cave wētā of New Zealand (Macropathinae) are among the largest members, reaching sizes comparable to small birds.

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Appearance

Medium to large orthopterans with body lengths ranging from 9–35 mm and leg spans up to 10 cm. Body typically brownish, humpbacked in profile, and always wingless. arise closely adjacent on the and are exceptionally long, often exceeding body length. Hind legs enlarged with drumstick-shaped and long, slender tibiae adapted for jumping. Some possess modified hind leg armaments including enlarged femora with spines and bent tibiae. Early instars may appear translucent. Females bear a prominent, blade-like ovipositor projecting from the . present, serving sensory functions.

Habitat

Primarily associated with cool, damp, dark microhabitats. Natural environments include caves, mine shafts, animal burrows, hollow trees, rotten logs, stumps, leaf litter, and under stones or boards. Some specialized for sand dunes (sand treaders) or alpine areas near permanent ice. Frequently encountered in human-modified environments including basements, cellars, garages, crawl spaces, wells, drains, sewers, and greenhouses. High moisture dependence drives selection.

Distribution

Worldwide distribution with major radiations in North America (Ceuthophilinae), New Zealand and Australia (Macropathinae), Asia (Aemodogryllinae, Rhaphidophorinae), and the Mediterranean (Troglophilinae, Dolichopodainae). Gondwanan distribution pattern in Macropathinae includes South America, South Africa, Falkland Islands, Tasmania, and New Zealand. Asian camel crickets (Diestrammena, Tachycines) introduced to North America and Europe, now widespread in greenhouses and urban buildings.

Seasonality

Activity patterns vary by . Cave-dwelling active year-round in stable environments. Surface-dwelling species most active during warmer months. Home invasion by Asian camel crickets peaks late summer through early autumn. Some species phenologically isolated at same sites (e.g., Pristoceuthophilus arizonae active September–October vs. P. 'Huachuca summer' active July).

Diet

scavengers consuming decaying organic matter including leaves, roots, fruits, fungi, and detritus. Known to feed on rotting insect remains, including conspecifics. Captive specimens accept oatmeal, molasses, and commercial pet food. Occasional on weakened or injured documented. Some damage paper products, fabrics, and young plants in greenhouses.

Host Associations

Life Cycle

Hemimetabolous development with , nymph, and stages. Eggs deposited in soil or substrate using sword-like ovipositor. Nymphs resemble smaller adults; early instars may appear translucent. Development rate varies by temperature and stability. Some reach adulthood within single season; others with extended development. Adults collected July–October in studied Pristoceuthophilus species. Longevity in wild poorly documented.

Behavior

Strictly , emerging from daytime shelters to forage. Highly moisture-dependent; aggregates in favorable microhabitats. Exhibits thigmotaxis, traveling with body contact against walls and surfaces. Remarkable jumping ability—can clear obstacles ten times body height. (voluntary leg detachment) observed when captured, with missing legs sometimes regenerating. Some display male-male combat using modified hind legs for grappling. Sexual coercion via hind leg clamping documented in Pristoceuthophilus. Defensive jumping to escape in low-light conditions.

Ecological Role

Important scavengers in cave and forest , processing decaying organic matter and contributing to nutrient cycling. Sand treaders serve as prey for specialized including scorpions and LeConte's thrasher (Toxostoma lecontei) in desert dune systems. for parasitic mites. Food source for various cave-dwelling predators. Role in cave ecosystem energy flow significant due to high in some systems.

Human Relevance

Occasional nuisance in buildings, particularly basements, garages, and crawl spaces. Asian camel crickets (Diestrammena/Tachycines) have become indoor invaders in eastern North America, outcompeting native Ceuthophilus in urban environments. Rarely cause damage beyond minor fabric nibbling and fecal staining. No medical or veterinary significance; completely harmless despite intimidating appearance. Used as fish . Greenhouse species occasionally damages young plants. Subject of cave conservation concern due to specificity of some species.

Similar Taxa

Misconceptions

The prominent ovipositor is frequently mistaken for a stinger, but are entirely harmless to humans. The '' leads to confusion with true crickets (Gryllidae), though they are not closely related and cannot produce sound. Spider-like appearance and jumping cause unnecessary alarm. Not all are restricted to caves—many occupy surface . Asian species now common in homes are often assumed native.

More Details

Invasion Biology

Asian camel crickets (Diestrammena asynamora, Tachycines asynamorus, D. japanica) established in North America before 1900, now in urban indoor environments from Maryland to California. National survey found >90% of home-invading camel crickets in mid-Atlantic region were Asian , displacing native Ceuthophilus. These species also invade natural caves, potentially competing with native fauna.

Male Armaments

Pristoceuthophilus exhibits unique dual-purpose hind leg modifications: enlarged spiny and bent tibiae used both in male-male combat and sexual coercion of females. Represents evolutionary exaptation where intrasexual weapons acquired secondary mating function.

Cave Adaptations

Cavernicolous show reduced or blindness, elongated appendages for enhanced tactile sensing in darkness, and pale or translucent . Some species persist near permanent ice in alpine zones. New Zealand cave wētā include among the largest orthopterans globally.

Collection Methods

Entomologists attract camel crickets using oatmeal trails or molasses smeared on tree trunks and logs, returning at night to collect. Sticky traps effective indoors, particularly at wall corners where thigmotactic concentrates activity.

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Sources and further reading