Woodlouse Spider, Woodlouse Hunter, Sowbug Killer, Slater Spider
Dysdera crocata
Dysderidae (Woodlouse Hunters), Order Araneae
Physical Description
Elongated oval body shape with a distinctive reddish-brown to dark chestnut carapace and a smooth, unpatterned cream to tan-gray oval abdomen. Most notable for its enlarged, forward-projecting chelicerae (jaws) and long reddish fangs designed to pierce hard exoskeletons. Lacks prominent hairs, giving it a shiny or leathery appearance.
Size Estimate
Body length typically 11-15 mm for females and 9-10 mm for males, with a leg span of 25-40 mm. This specimen appears to be an adult or sub-adult based on body proportions.
Coloration & Markings
Deep reddish-orange to dark brownish-red cephalothorax, dark reddish-orange legs, and a contrasting pale greyish-tan to yellowish-cream abdomen without distinct patterns or markings.
Web Type
Does not spin prey-capture webs. It is an active ground-hunting nocturnal predator that constructs a flattened, silk retreat sac under logs, rocks, leaf litter, or bark where it rests during the day.
Eye Arrangement
Six small eyes arranged closely together in an oval ring or semi-circular cluster near the front of the carapace, a key diagnostic trait for the family Dysderidae.
Leg Characteristics
Medium to long reddish-orange legs, moderately robust, smooth with sparse fine spines. Legs I and II are directed forward when resting or hunting, aiding in maneuvering beneath tight bark or stones.
Venom & Safety Information
Venom Information
Cytotoxic components designed to subdue small arthropods. Venom is low in toxicity to humans and not medically significant. Bite may cause localized pain comparable to a bee sting, accompanied by mild swelling and redness lasting a few hours to days.
Medical Significance
Harmless to humans in terms of systemic danger. Bites are non-lethal and minor. Basic wound care (washing with soap and water, applying a cold pack) is usually sufficient. Seek medical care only if secondary bacterial infection or severe allergic reaction occurs.
Safety Recommendations
Do not pick up with bare hands as large fangs can pierce human skin defensively. If found indoors, easily relocate using the cup-and-cardboard method. Ensure basements remain dry to reduce woodlouse prey that attracts them.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; native to the Mediterranean region but widely introduced across North America, Europe, Australia, New Zealand, and South America. Commonly found outdoors under logs, stones, brick piles, and mulch, as well as indoors in damp areas like basements, cellars, and crawlspaces.
Behavior & Temperament
Nocturnal active hunter. Slow-moving normally, but capable of quick bursts when chasing prey or threatened. Docile unless handled or accidentally squeezed, at which point it will display open fangs in a defensive threat posture.
Diet & Prey
Specialized predator primarily feeding on woodlice (isopods, sowbugs, pillbugs). Fangs are specifically adapted to squeeze around or pierce through the armored plates of woodlice. Also consumes silverfish, beetles, and other ground-dwelling invertebrates.
Seasonal Activity
Active year-round in warm indoor environments or climate-controlled shelters; peak outdoor activity occurs from late spring through autumn when prey populations soar. Overwinters inside silken sacs under debris.
Description
The Woodlouse Spider (Dysdera crocata) is an easily recognizable ground hunter famous for its striking reddish carapace and pale, egg-shaped abdomen. Equipped with impressive, oversized fangs, it specializes in hunting terrestrial isopods. While its intimidating appearance and large jaws often alarm homeowners, it is a non-aggressive, beneficial predator that aids in indoor and garden pest control.
Key Features
Six eyes in a tight cluster, bright reddish-brown carapace and legs, pale unpatterned abdomen, and exceptionally long, forward-pointing chelicerae and fangs.
Similar Species
Broad-faced Sac Spider (Trachelas tranquillus) - has similar red carapace/tan abdomen, but possesses eight eyes in two rows and smaller fangs. Slender Sac Spider (Clubiona spp.) - paler coloration with different eye arrangement. Ground Spiders (Gnaphosidae) - generally darker with tubular spinnerets.
Life Cycle
Females lay 20 to 70 eggs inside a silken retreat sac during spring or summer. Females guard the eggs and young spiderlings until their first molt. Lifespan is relatively long for spiders, often reaching 2 to 3 years.
Ecological Importance
Serves as an essential natural predator controlling populations of isopods, sowbugs, and other soil-dwelling invertebrates in gardens, forests, and suburban landscapes.
Conservation Status
Not evaluated by the IUCN (Not Threatened). Extremely common and stable global population due to synanthropic distribution alongside humans.
Interesting Facts
Its long fangs act like pliers, enabling it to puncture the armored dorsal shell of woodlice or flip them over to bite their soft belly. Unlike the vast majority of spiders which have eight eyes, Dysdera crocata has only six.
Photography Tips
Focus on the head region to capture the six grouped eyes and prominent red chelicerae. A low-angle macro shot highlighting the contrast between the shiny red carapace and pale abdomen provides the best identification profile.
Identified: 2026-07-26T21:34:39.625556