Woodlouse Spider, Woodlouse Hunter, Sowbug Killer
Dysdera crocata
Dysderidae (Woodlouse Hunters), Order Araneae. Key family traits include six eyes arranged in a tight oval and large, forward-pointing chelicerae (fangs).
Physical Description
A distinctive medium-sized spider with a smooth, dark reddish-brown cephalothorax, large, prominent reddish chelicerae with long black fangs, and a oval, cream-to-tan gray smooth abdomen without markings.
Size Estimate
Body length is approximately 10 to 15 mm (0.4 to 0.6 inches) for females and slightly smaller for males, with a leg span around 25 to 35 mm. The specimen appears to be an adult or sub-adult.
Coloration & Markings
Bright to dark reddish-orange cephalothorax and legs, contrasting sharply with a pale yellowish-tan, greyish, or buff-colored, unpatterned abdomen.
Web Type
Non-web-building hunting spider. It constructs a flattened, tubular silk sac in hidden crevices or under debris solely for resting, molting, and egg-laying.
Eye Arrangement
Six eyes (rather than eight) clustered closely together in a small semi-circular or oval arrangement on the front of the carapace.
Leg Characteristics
Moderately long, robust reddish-orange legs. Lacks heavy banding. Adapted for crawling through soil, leaf litter, and tight spaces.
Venom & Safety Information
Venom Information
Contains mild cytotoxic components tailored to subduing armored arthropods. The venom is not medically significant to humans.
Medical Significance
Low medical importance. Bites are rare and usually occur when crushed. The bite can be temporarily painful (like a minor bee sting) due to large fangs, occasionally causing localized redness or mild swelling, but requires no special medical intervention.
Safety Recommendations
If found indoors, safely relocate the spider outdoors using a glass and stiff piece of paper. Avoid handling with bare hands to prevent a nip from its large fangs.
Habitat & Behavior
Habitat & Range
Originally native to the Mediterranean region, now cosmopolitan and widely naturalized across North America, Europe, Australia, and parts of South America. Commonly found under logs, rocks, leaf litter, woodpiles, basements, and humid indoor areas.
Behavior & Temperament
Nocturnal, solitary hunter. Slow-moving unless disturbed, but capable of defending itself if pinched or pressed. Not aggressive toward humans.
Diet & Prey
Specialized predator of terrestrial isopods (woodlice, sowbugs, pillbugs). Uses its oversized chelicerae to pierce the tough exoskeleton or flip isopods over to bite their soft undersides.
Seasonal Activity
Active year-round in warm indoor environments or southern climates; outdoors, adults are most visible during spring and summer nights.
Description
The Woodlouse Spider is an easily recognizable ground hunter distinguished by its fiery red-brown head, pale smooth abdomen, and formidable forward-facing fangs. Specialized for preying on armored pillbugs, it roams damp, dark microhabitats at night.
Key Features
Distinct reddish-orange cephalothorax and legs paired with a pale unpatterned abdomen; six closely grouped eyes; exceptionally large chelicerae (fangs) projecting forward.
Similar Species
Broad-faced Sac Spider (Trachelas tranquillus) which has eight eyes and smaller fangs; Slender Sac Spiders (Cheiracanthium spp.) which are uniformly pale yellowish-green.
Life Cycle
Females produce a silk egg retreat containing 20-70 eggs and guard them until hatching. Spiderlings undergo several molts. Lifespan can reach 2 to 3 years.
Ecological Importance
Serves as an important natural biological control agent for terrestrial isopods and other detritivores in gardens, compost heaps, and damp indoor spaces.
Conservation Status
Not evaluated by the IUCN. Highly adaptable and abundant globally in human-modified and natural landscapes.
Interesting Facts
Its huge fangs evolved specifically as a pair of pincers/can-openers to pierce the thick chitinous armor of woodlice. Despite its fierce look, it poses virtually no danger to humans.
Photography Tips
Focus sharply on the cephalothorax and chelicerae from a front-three-quarter angle using macro lighting to highlight the six-eye layout and smooth texture.
Identified: 2026-07-25T22:35:45.867710