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Dysdera crocata is the only representative of the family Dysderidae in the United States. The family Dysderidae is native to the western Palearctic, with most species found in the Mediterranean region, but D. crocata has spread widely around the world. In the Nearctic, it occurs mainly in urban areas and disturbed habitats.
Dysdera crocata has an orange-brown cephalothorax (the portion of a spider's body to which the legs attach) as well as similarly colored chelicerae and legs. The long, essentially hairless abdomen is gray to whitish. The chelicerae are very large and held out conspicuously. On the chelicerae are combs of long bristles and terminal fangs that are nearly as long as the chelicerae. Female length is 11 to 15 mm, male length is 9 to 10 mm.
Although these spiders may bite if they feel threatened, based on the cases that have been documented, the effect of the bite on humans is minor and may be mainly or entirely due to mechanical piercing of the skin rather than the spider's venom (Vetter and Isbister 2006).
These wandering nocturnal hunters spiders live under stones, under loose tree bark, and in other similar dark, humid locations in both grasslands and forests. Although they do not spin a web, they do spin a tough oval silken retreat hardly larger than the spider.
Dysdera crocata is often said to be a specialist feeder on terrestrial isopods (woodlice). Although it is unclear how specialized this species is in nature (they will take a range of prey in captivity), some dysderid species (including this species) are known to feed on woodlice in the wild and have modified chelicerae and feeding behavior that appears clearly to indicate at least some degree of specialization on these prey (Pollard et al. 1995; Řezáč and Pekár 2007 and references therein; Řezáč et al. 2008).
(Comstock and Gertsch 1948; Kaston 1978; Howell and Jenkins 2004; Ubick 2005)