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Pseudoscorpiones (pseudoscorpions; subphylum Chelicerata, class Arachnida) Order of minute arachnids whose name refers to their large, scorpion-like, chelate pedipalps which do not, however, possess a stinging organ. Pseudoscorpions are flattened, with the oval opisthosoma joined broadly to the prosoma. Most are black, brown, or brownish-green, and have two pairs of respiratory tracheae. Few are more than 5 mm long, although the largest species reaches 12 mm. The sides of the carapace bear one or two pairs of eyes, and the small chelicerae produce silk for the construction of moulting, overwintering, and brooding chambers. Prey items are caught by means of the large, chelate pedipalps, and are passed to the chelicerae where digestive juices are injected. Most species live in crevices and the humid conditions found under bark plant litter, etc., and feed on Collembola, caterpillars, and ants. Some pseudoscorpions disperse by phoresy (clinging to the legs of passing flies and other animals). Courtship displays occur, and may involve pheromones; and there are indications of presocial behaviour in this order of often gregarious species. 2000 species occur world-wide, of which 25 can be found in the UK. Some species inhabit houses and are cosmopolitan, hunting booklice, nymphal bedbugs, and other small insects.


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pseudoscorpions See PSEUDOSCORPIONES.

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