Woodlouse Spider, Woodlouse Hunter, Sowbug Killer
Dysdera crocata
Dysderidae (Woodlouse Spider Family), Order Araneae. Key family characteristics include six eyes arranged in a compact, tight group on the front of the head and unusually large, forward-pointing chelicerae (jaws).
Physical Description
Elongated body shape featuring a dark, reddish-brown to orange-brown carapace and a smooth, shiny, cylindrical pale pinkish-beige or yellow-gray abdomen. The most striking anatomical feature is its pair of oversized, formidable chelicerae adapted specifically for piercing the hard exoskeletons of woodlice.
Size Estimate
Body length typically ranges from 10 to 15 millimeters for females, with males slightly smaller (9 to 11 millimeters). The leg span is around 20 to 25 millimeters. The specimen in the image appears to be a small juvenile or sub-adult.
Coloration & Markings
Characterized by a distinctly contrasting color palette: a glossy dark reddish-brown or mahogany head and thorax, orange-brown legs, and a drab beige, ivory, or pale pinkish-gray unpatterned abdomen.
Web Type
Woodlouse spiders do not spin webs to catch prey. Instead, they construct a silken retreat or daytime shelter under rocks, logs, bark, or inside damp areas like basements and sinks, where they rest during daylight hours.
Eye Arrangement
Equipped with six eyes arranged closely together in a compact, oval or horseshoe-shaped cluster on the anterior portion of the cephalothorax.
Leg Characteristics
Legs are relatively short, robust, and tapering, colored a uniform reddish-orange or yellowish-brown. They are equipped with fine spines and hairs, allowing the spider to maneuver efficiently in tight crevices and leaf litter.
Venom & Safety Information
Venom Information
Possesses mild, non-lethal venom used primarily to immobilize invertebrate prey. The venom is not considered medically significant to humans and rarely causes more than localized discomfort.
Medical Significance
Harmless to humans. While a bite can break the skin due to the impressive size of the fangs, resulting in mild pain, localized redness, and minor swelling, it poses no serious medical danger and does not require professional medical intervention.
Safety Recommendations
No special pest control is necessary. If found in a sink, simply place a cup over the spider, slide a piece of paper underneath, and release it outdoors in a damp garden area.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, native to Europe but now widely introduced across North America, Australia, New Zealand, and parts of South America. Prefers damp, dark microhabitats such as under logs, stones, garden mulch, and occasionally inside homes near sinks or basements where moisture accumulates.
Behavior & Temperament
Nocturnal hunters that emerge at night to actively forage for prey. They are generally docile toward humans and will only bite if firmly pressed against the skin, though their large fangs can deliver a surprisingly sharp pinch.
Diet & Prey
Specialized diet consisting almost exclusively of woodlice (sowbugs and pillbugs). They use their massive, elongated chelicerae to pierce the armored shell of the crustacean from the side, bypassing the hard dorsal plates.
Seasonal Activity
Most active during spring, summer, and autumn. During colder winter months, they seek out deep shelter under logs, rocks, or within human structures to overwinter.
Description
The Woodlouse Spider is an unmistakable hunter easily recognized by its shiny reddish-brown front half and pale abdomen, coupled with disproportionately large jaws. Frequently found wandering into sinks or bathtubs while searching for moisture, this specialized predator is entirely harmless to humans while serving as a dedicated controller of garden pests.
Key Features
Six eyes in a tight cluster, remarkably large protruding chelicerae, glossy reddish-brown cephalothorax, and a pale, unpatterned cylindrical abdomen.
Similar Species
Can occasionally be confused with broad-faced sac spiders (Trachelas tranquillus) or wood spiders, but can be definitively distinguished by its six eyes (instead of eight), elongated jaws, and distinct color contrast.
Life Cycle
Females construct silken egg sacs in secluded retreats during spring, laying around 60 to 70 eggs. The mother guards the eggs and newly hatched spiderlings. They undergo several molts to reach maturity, with a typical lifespan of 1.5 to 2 years.
Ecological Importance
Acts as an effective natural controller of woodlouse (sowbug) populations in gardens and subterranean habitats, helping maintain ecological balance in leaf litter and soil food webs.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and frequently benefit from human-altered garden environments.
Interesting Facts
Despite feeding on armored woodlice that accumulate high levels of heavy metals in their bodies, woodlouse spiders are remarkably resilient to toxicity. Their huge fangs can open remarkably wide to grasp prey much broader than themselves.
Photography Tips
Use macro lenses with adequate lighting to highlight the glossy texture of the cephalothorax and the impressive size of the chelicerae. Photograph from a top-down or slight side angle while the spider is on a neutral surface.
User Notes
Found in sink
Identified: 2026-10-15T03:23:36.167045