Woodlouse Spider, Woodlouse Hunter, Pillbug Hunter
Dysdera crocata
Dysderidae (Woodlouse Hunter Family), Order Araneae. Key family characteristics include six eyes arranged in a compact, tight group on the front of the head and extremely large, forward-pointing chelicerae (fangs) adapted for piercing armored prey.
Physical Description
The woodlouse spider features a distinctive elongated body plan with a dark reddish-brown to mahogany cephalothorax and a smooth, shiny, pale beige to yellowish-pink oblong abdomen. Its most striking physical feature is its massively enlarged chelicerae that protrude forward, specifically designed to impale hard-shelled crustaceans.
Size Estimate
Body length typically ranges from 11 to 15 millimeters for females and 9 to 10 millimeters for males, with a moderate leg span proportional to its body. The specimen in the image appears to be a typical adult or sub-adult.
Coloration & Markings
The cephalothorax, legs, and mouthparts are a deep, glossy dark red or reddish-brown. The abdomen is unpatterned, smooth, and ranges from pale pinkish-gray to yellowish-white, lacking distinct stripes, chevrons, or spots.
Web Type
Dysdera crocata does not spin webs to catch prey. Instead, it constructs a silken retreat, often a flattened sac under stones, logs, or loose bark, where it rests during the day.
Eye Arrangement
Six eyes arranged in a compact, tight oval cluster near the front center of the cephalothorax, typical of the family Dysderidae, differing from the standard eight-eyed pattern found in most other spiders.
Leg Characteristics
Legs are stout, relatively short, colored matching the reddish-brown cephalothorax, and equipped with spines to help secure struggling, armored prey like woodlice.
Venom & Safety Information
Venom Information
Possesses venom designed specifically to immobilize small arthropods. It is generally low in toxicity to humans and non-lethal, though mechanical puncture from the large fangs can be painful.
Medical Significance
Not medically significant. A bite may cause minor, localized pain, redness, and swelling that typically resolves within a day without medical intervention. Secondary infection is rare but possible if the wound is not kept clean.
Safety Recommendations
Avoid bare-handed handling. If found indoors, gently capture it with a cup and piece of paper and release it outdoors under a rock or log.
Habitat & Behavior
Habitat & Range
Originating in Europe, Dysdera crocata has been widely introduced globally, including North America, Australia, and parts of South America. It prefers damp environments under logs, rocks, bricks, and leaf litter, frequently venturing into human dwellings in search of its preferred prey.
Behavior & Temperament
Primarily nocturnal active hunters, woodlouse spiders spend daylight hours hidden in silken retreats. They are not aggressive toward humans but will deliver a defensive bite if handled or trapped against the skin.
Diet & Prey
Specialized almost exclusively in feeding on woodlice (isopods, pillbugs, and sowbugs). They use their exceptionally long, powerful fangs to pierce the tough dorsal shell of an isopod while avoiding its toxic defensive secretions.
Seasonal Activity
Active from spring through autumn, often moving indoors during damp or cooler weather when moisture levels fluctuate outdoors.
Description
Dysdera crocata, widely known as the woodlouse spider, is an easily recognizable and specialized nocturnal hunter. With its striking shiny reddish-brown front half, pale oblong abdomen, and formidable protruding fangs, it is a specialized predator of pillbugs and sowbugs found commonly in gardens and around foundations.
Key Features
Distinguished by its dark reddish-brown cephalothorax, pale pinkish-beige unpatterned abdomen, six-eyed cluster, and exceptionally large, forward-pointing chelicerae adapted for piercing woodlice.
Similar Species
Can occasionally be confused with other ground-dwelling wandering spiders such as Trachelas pacificus or broad-faced sac spiders (Trachelas tranquillus), but those lack the massive forward-pointing fangs and specialized coloration of Dysdera crocata.
Life Cycle
Females construct a silken egg sac where they lay around 70 eggs, often guarding the eggs and young spiderlings. They can live for several years, undergoing regular molting within protected retreats.
Ecological Importance
Acts as a primary specialist predator of woodlice (isopods) in garden and woodland ecosystems, helping to regulate population numbers of these detritivores.
Conservation Status
Not evaluated by the IUCN, but populations are secure, highly abundant, and cosmopolitan due to human introduction.
Interesting Facts
Despite their intimidating, monstrous appearance due to oversized fangs, they are completely harmless to humans and play a crucial role in controlling garden isopod populations.
Photography Tips
Photograph from a side or three-quarter angle to clearly highlight the elongated reddish cephalothorax and oversized chelicerae. Use macro lenses with diffuse lighting to avoid harsh glare on its shiny carapace.
Identified: 2026-08-25T01:23:02.524732