Chelifer cancroides

Distinguished from other Cheliferidae by: carapace with large setose tubercles; male carapace and tergites I-VII/VIII with distinct lateral keels; cheliceral hand with 4 setae and lacking seta sbs; adult tarsal claws with lateroventral process (except first leg pair of adult males); denticulate subterminal tarsal setae; male coxa IV strongly arcuate with large lateral process. The genus Chelifer is currently monotypic, with all other described species synonymized or transferred to other genera.

Body teardrop-shaped, 2.5–4.5 mm in length, with rich mahogany coloration. Pedipalps very long, 7–9 mm when extended. Abdomen with 12 segments, only 10 easily visible. Cephalothorax with one pair of eyes. Carapace bearing large setose tubercles. Males with distinct lateral keels on carapace and tergites I-VII or I-VIII. Cheliceral hand with 4 setae, lacking seta sbs. Tarsal claws of adults with lateroventral process (except first leg pair of adult males). Subterminal tarsal setae denticulate.

Occurs in diverse environments including under tree bark, caves, bird nests, and beehives. Frequently found riding on bats, flies, and hymenopterans. Strongly synanthropic in human structures: houses, stables, barns, and chicken coops.

Cosmopolitan distribution across North America, Europe, Africa, Australia, Caribbean, Middle America, and Northern Asia (excluding China). Most widely distributed pseudoscorpion species globally.

Feeds on small arthropods including psocids, fruit flies, and mites. Preys on Varroa destructor in beehives. Venomous pedipalps used to subdue prey.

• Apis mellifera - commensal/predatorOccurs in beehives; preys on Varroa destructor mites parasitizing honey bees
• Varroa destructor - preyActively predated upon in beehive environments
• bats - phoresyHas been observed riding on bats
• flies - phoresyHas been observed riding on flies
• hymenopterans - phoresyHas been observed riding on hymenopterans

Development from egg to maturity takes 10–24 months, requiring three molts. Molting may involve construction of silk nest. Fecundity 20–40 eggs. Lifespan typically 3–4 years.

Males maintain small mating territories, few centimeters in size. Upon female entry, male initiates mating dance and deposits spermatophore, which female picks up. During forward locomotion, exhibits frequent microstops of 100–200 ms duration. Performs statically stable alternating tetrapod gait during forward and backward walking, with nearly complete inversion of tetrapod schemes between directions. Achieves highest speeds (up to 17 body lengths per second) during backward locomotion as escape behavior. Forward walking characterized by lower speeds and ~10% phase shifts between loosely coupled leg groups within tetrapod. Second leg pair plays special role, likely for stability related to large pedipalps. Capable of upside-down walking at low speeds up to 4 body lengths per second, without rigidly fixed leg coordination.

Predator of small arthropods in diverse microhabitats. Potential biological control agent for Varroa destructor in managed honey bee colonies.

Synanthropic and harmless to humans. Occurs commonly in houses and outbuildings. Of interest in apiculture for potential control of Varroa destructor mites. Venom has demonstrated toxicity to methicillin-resistant Staphylococcus aureus, fungi, and other arthropods.

• Other CheliferidaeDistinguished by combination of carapace setose tubercles, male lateral keels, cheliceral setation, tarsal claw morphology, and male genitalia structure. The genus Chelifer is monotypic, making species-level identification straightforward once family assignment is confirmed.

• cosmopolitan
• synanthropic
• harmless to humans
• predator
• venomous pedipalps
• phoretic
• biological control potential

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Notes on the Life History of the Pseudoscorpion Chelifer cancroides (Linn.) (Chelonethida).
• Locomotion in the pseudoscorpionChelifer cancroides: forward, backward and upside-down walking in an eight-legged arthropod
• Anatomy of the Nervous System in Chelifer cancroides (Arachnida: Pseudoscorpiones) with a Distinct Sensory Pathway Associated with the Pedipalps
• Predation behaviour of the pseudoscorpion, Chelifer cancroides , against Varroa destructor in the presence and absence of alternative prey and Apis mellifera