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)
- Comstock, J.H. (revised and edited by W.J. Gertsch). 1948. The Spider Book, Comstock Publishing Company, Ithaca, New York.
- Howell, W.M. and R.L. Jenkins. 2004. Spiders of the Eastern United States: a Photographic Guide. Pearson Education, Boston.
- Kaston, B.J. 1978. How to Know the Spiders, 3rd edition. Wm. C. Brown Company, Dubuque, Iowa.
- 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 Dysdera 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.
- Ubick, D. 2005. Dysderidae. P. 103 in D. Ubick, P. Paquin, P.E. Cushing, and V. Roth (eds.). Spiders of North America: an Identification Manual. American Arachnological Society.
- Vetter, R.S. and G.K. Isbister. 2006. Verified bites by the woodlouse spider, Dysdera crocata. Toxicon 47: 826-829.
- Müller, Y. (2004). Faune et flore du littoral du Nord, du Pas-de-Calais et de la Belgique: inventaire. [Coastal fauna and flora of the Nord, Pas-de-Calais and Belgium: inventory]. Commission Régionale de Biologie Région Nord Pas-de-Calais: France. 307 pp. http://www.marinespecies.org/aphia.php?p=sourcedetails&id=9269
- Gordon, D. (Ed.) (2009). New Zealand Inventory of Biodiversity. Volume One: Kingdom Animalia. 584 pp http://www.marinespecies.org/porifera/porifera.php?p=sourcedetails&id=145244
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Molecular Biology and Genetics
Barcode data: Dysdera crocata
There are 7 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Dysdera crocata
Public Records: 4
Specimens with Barcodes: 8
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Rounded National Status Rank: NNR - Unranked
The woodlouse spider (Dysdera crocata) is a species of spider that preys exclusively upon woodlice. Other common names refer to variations on the common name of its prey. These are woodlouse hunter, sowbug hunter, sowbug killer, pillbug hunter and slater spider.
Female specimens are 11–15 mm long while males are 9–10 mm. They have a dark-red cephalothorax and legs, and a shiny (sometimes very shiny) yellow-brown abdomen. Notably, they have disproportionately large chelicerae. Dysdera crocata is difficult to distinguish from the much less common Dysdera erythrina though this species is not often found near human habitation.
They are usually to be found under logs in warm places, often close to woodlice. They have been found in houses. They spend the day in a silken retreat made to enclose crevices in, generally, partially decayed wood, but sometimes construct tent-like structures in indents of various large rocks. Woodlouse spiders hunt at night without the use of a web. Their diet consists exclusively of woodlice which—despite their tough exoskeleton—are pierced easily by the spider's large chelicerae.
The courtship of these spiders is typically aggressive and mates risk injury from each other's large chelicerae. The female lays her eggs in a silken sac and is believed to look after her young after hatching like the "Mothercare" spider (Theridion sisyphium).
They have been known to bite humans if handled. Their bite can be painful but the venom causes no major medical problems. Localised itchiness at the bite site has been reported in some cases. 
- Cooke, J. A. L. (June 1965), "Systematic aspects of the external morphology of Dysdera crocata and Dysdera erythrina (Araneae, Dysderidae)", Acta Zoologica 46 (1-2): 41–65, doi:10.1111/j.1463-6395.1965.tb00726.x
- Vetter, R.S.; Isbister, G.K. (2006). "Verified bites by the woodlouse spider, Dysdera crocata". Toxicon 47 (7): 826–829. doi:10.1016/j.toxicon.2006.02.002. PMID 16574180. Retrieved 2010-01-06.
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