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 spead widely around the world. In the Nearctic, it occurs mainly in urban areas and disturbed habitats. In the wild, the preferred prey is terrestrial isopods.
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 effects 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 spiders live under stones and loose tree bark and similar dark, humid locations in both grasslands and forests.They do not spin a web although they do spin a tough oval silken retreat hardly larger than the spider. They are nocturnal wandering hunters.
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 have modified chelicerae and feeding behavior that appears clearly to indicate specialization on woodlice (Pollard et al. 1995; Řezáč and Pekár 2007 and references therein; Řezáč et al. 2008)
Pollard, S.D., R.R. Jackson, A. Vanolphen, and M.W. Robertson. 1995. Does Dysdera crocata (Araneae: Dysderidae) prefer woodlice as prey? Ethology, Ecology and Evolution 7(3): 271-275.
Řezáč, M. and S. Pekár. 2007. Evidence for woodlice-specialization in <i>Dysdera<i/> spiders: behavioural versus developmental approaches Physiological Entomology 32: 367-371.
Řezáč, M., S. Pekár, and Y. Lubin. 2008. How oniscophagous spiders overcome woodlouse armour. Journal of Zoology 275: 64-71.
Vetter, R.S. and G.K. Isbister. 2006. Verified bites by the woodlouse spider, <i>Dysdera crocata</i>. Toxicon 47: 826-829.