Woodlouse Hunter, Sowbug-killer, Woodlouse Spider
Dysdera crocata
Dysderidae (Woodlouse Hunters), Order Araneae
Physical Description
A striking spider with a smooth, glossy, elongated cephalothorax and a pale, oval-shaped abdomen. It features exceptionally large, forward-pointing chelicerae (fangs) designed for piercing tough exoskeletons. The body is hairless in appearance, giving it a sleek, 'oily' texture.
Size Estimate
Body length typically ranges from 9-15 mm (0.35-0.6 inches). Leg span can reach up to 25-30 mm. This specimen appears to be an adult female based on the large abdomen size.
Coloration & Markings
Distinctive bi-coloration: the cephalothorax and legs are a deep reddish-orange or mahogany, while the abdomen is a contrasting creamy-grey, tan, or beige with no markings.
Web Type
This is a wandering hunter that does not build webs for prey capture. It constructs small, oval, silken retreats under rocks or logs for resting, molting, and protecting egg sacs.
Eye Arrangement
Six monostichous (highly grouped) eyes arranged in a tight semi-circle or oval near the front of the cephalothorax. This 'six-eye' configuration is a diagnostic feature of the Dysderidae family.
Leg Characteristics
Six legs are reddish-orange, matching the cephalothorax. They are moderately long and robust, lacking conspicuous spines but ending in claws adapted for navigating uneven terrain and leaf litter.
Venom & Safety Information
Venom Information
The venom is not considered medically significant to humans. While it is highly effective against crustaceans like woodlice, it is relatively weak against mammals. Reactions are typically localized.
Medical Significance
Low danger level. Bites are rare and usually occur when the spider is pressed against skin. Symptoms include localized pain (similar to a bee sting), itching, and redness that typically resolves within 48 hours without treatment.
Safety Recommendations
Use a cup and stiff paper to relocate them outdoors to a garden bed or woodpile. In basements, reducing moisture and removing debris (which attracts their prey) will naturally discourage their presence.
Habitat & Behavior
Habitat & Range
Commonly found in North America, Europe, and parts of Australia/Asia. It prefers moist, dark environments such as under rocks, rotting logs, leaf litter, and in damp basements or crawl spaces.
Behavior & Temperament
A nocturnal active hunter. During the day, it hides in silk retreats. It is not aggressive but will defend itself if handled. Its primary behavior is searching for specific prey in crawl spaces or gardens.
Diet & Prey
Specialized feeder focusing on woodlice (pill bugs/sowbugs). It uses its oversized fangs to reach around and pierce the soft underbelly of the woodlouse's armored shell. It may also eat other ground-dwelling invertebrates.
Seasonal Activity
Year-round in warmer climates or indoors, but most active from spring through autumn. They often enter homes in the autumn seeking moisture or prey.
Description
The Woodlouse Hunter is an impressive ground-dwelling specialist easily recognized by its 'brick-red' front and 'parchment' back. It is a beneficial predator that helps control populations of isopods in gardens and around home foundations.
Key Features
Reddish-brown cephalothorax, cream-colored abdomen, six eyes (not eight), and massive, protruding chelicerae.
Similar Species
Often confused with the Broad-Faced Sac Spider (Trachelas tranquillus), which has eight eyes and different leg proportions, or the Brown Recluse, though the Woodlouse Hunter lacks the 'violin' mark and has a much darker cephalothorax.
Life Cycle
Females lay about 70 eggs in a silk retreat and stay with them initially. They do not demonstrate the extensive maternal care seen in some other families. Individuals can live for 2-3 years, which is long for many spiders.
Ecological Importance
Critical for natural pest control of woodlice and other detritivores. They help balance the soil ecosystem by regulating populations of organisms that break down organic matter.
Conservation Status
Not evaluated by the IUCN, but considered common and widespread with stable populations in urban and suburban landscapes.
Interesting Facts
Despite their frightening fangs, they are almost exclusively interested in eating isopods. Their fangs can pivot significantly to find the vulnerable gaps in a sowbug's armor.
Photography Tips
Focus on the head area to capture the unique eye arrangement and large fangs. Since they are light-sensitive, avoid excessive flash which may cause them to scurry rapidly for cover.
Identified: 2026-06-15T01:23:03.346978