Pest profile

Woodlouse Spider

Dysdera crocata · Araneae: Dysderidae[4]

The woodlouse spider, or woodlouse hunter, is a Mediterranean spider now common around North American homes. It hunts sowbugs and pill bugs in damp places and looks fierce because of its large fangs, but it is considered beneficial.[1][2]

Woodlouse spider with a dark red head and legs and a pale pinkish-tan abdomen, seen from above on a white background
Woodlouse spider with a dark red head and legs and a pale pinkish-tan abdomen, seen from above on a white background. (c) Joss Carr, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • The front body section and legs are reddish orange to reddish brown, and the abdomen is dirty white, cream, gray or tan.[1][2][3]
  • Large, thick jaws and fangs point straight forward from the head, giving it a menacing look.[1][2]
  • It has six eyes, arranged in an oval.[1][2]
  • Females are about 11 to 15 mm long and males 9 to 10 mm, about 1/2 inch not counting legs.[1][3]

Where it lives

Native to the Mediterranean; in North America it is found from New England to Georgia and west to California.[1]

Biology and life cycle

It feeds mainly on sowbugs and pill bugs, which the British call woodlice, and also takes other arthropods.[1][2]

It lives under rocks, bark, mulch, plants, woodpiles and trash cans, in moist spots where isopods are plentiful.[2]

Adults probably overwinter; mating is reported in April, and females hang up to 70 eggs in a silken retreat, where spiderlings stay for a while.[1]

It turns up in and around homes mostly in spring and summer.[3]

Damage and signs

  • It causes no damage; it wanders indoors from damp outdoor habitat and helps by eating sowbugs and pill bugs.[2][3]

Health risk

It isn't known to be a health hazard. Bites have been linked to a small, intensely itchy red spot a few millimeters across, with no body-wide symptoms.[1][2]

Control

Prevention

Utah State University Extension also recommends changing exterior lighting to sodium vapor bulbs.[2]

Keep them out

Seal exterior cracks and crevices and install tight-fitting door sweeps on exterior doors.[2]

Sanitation

Reduce hiding places and moisture near the foundation, such as mulch, debris and woodpiles, and control sowbugs and pill bugs to remove its food.[2]

Traps and physical control

Vacuum spiders that get indoors, or catch them under a glass jar and release them outside.[2]

Pest monitors can capture spiders wandering in, especially from August to October.[2]

Common questions

Is the woodlouse spider dangerous?
No. Despite its big fangs it isn't considered a health hazard; a bite may cause a small, itchy red spot.[2][1]
Why do I find woodlouse spiders in my basement?
They follow their prey, sowbugs and pill bugs, which live in damp areas; cutting moisture and isopods near the house reduces them.[2][1]

Sources

  1. Penn State Extension, “Woodlouse Hunter Spider (updated September 8, 2025).” extension.psu.edu/woodlouse-hunter-spider (accessed 2026-10-06)
  2. Utah State University Extension, “Woodlouse Spider (IPM nuisance pest notes).” extension.usu.edu/planthealth/ipm/notes_nuisance/woodlouse-spider (accessed 2026-10-06)
  3. University of Minnesota Extension, “Woodlouse spider (What insect is this? Insects found indoors).” apps.extension.umn.edu/garden/diagnose/insect/indoor/relatives/medium/woodlouse-spider.html (accessed 2026-10-06)
  4. iNaturalist, “Dysdera crocata taxon page (order and family).” www.inaturalist.org/taxa/1454862 (accessed 2026-10-06)

Updated 2026-10-06. Built from sourced records. Spot an error? Tell us.