Mouse Spider (not to be confused with the Australian Mouse Spider), European Mouse Spider
Scotophaeus blackwalli
Gnaphosidae (Ground Spiders), Order Araneae
Physical Description
A medium-sized spider with a distinctive mouse-like appearance due to the fine, velvety grey hairs covering its abdomen. It has a flattened cephalothorax and a long, oval abdomen with prominent, cylindrical spinnerets at the rear.
Size Estimate
Body length: 8–12mm for females, 7–9mm for males. Total leg span can reach 20-30mm. This specimen appears to be an adult.
Coloration & Markings
The abdomen is a uniform, dull silvery-grey or mousy brown. The cephalothorax and legs are typically a shiny dark brown or reddish-brown. There are no distinct patterned markings like spots or stripes.
Web Type
They do not build hunting webs. Instead, they produce a small, thick, silk retreat or 'sac' in crevices where they hide during the day.
Eye Arrangement
Eight small eyes arranged in two rows of four. The posterior median eyes are often oval-shaped and slanted, which is characteristic of the Gnaphosidae family.
Leg Characteristics
Medium-length, robust legs designed for running. They are covered in fine hairs and lack the heavy banding seen in orb-weavers. In this image, several legs appear broken or curled due to trauma.
Venom & Safety Information
Venom Information
Contains mild enzymes used to paralyze prey. There is no evidence of neurotoxic or necrotic properties harmful to humans.
Medical Significance
Low danger level. Bites are rare and usually occur if the spider is squeezed. Symptoms typically include minor localized pain, redness, and swelling similar to a bee sting. No specific medical treatment is usually required.
Safety Recommendations
If found, it is best to relocate it outside using a cup and a piece of paper. They are not aggressive and do not pose a threat to pets or healthy humans.
Habitat & Behavior
Habitat & Range
Native to Europe but widely introduced to North America (Pacific coast and Northeast) and Australia. Frequently found inside homes, under bark, or in garden sheds.
Behavior & Temperament
Nocturnal active hunters. They wander at night to hunt prey rather than using a web. They are generally shy and will attempt to flee quickly when disturbed, though they can be defensive if restrained.
Diet & Prey
Feeds on small insects and other spiders. They are known to scavenge dead insects and can overpower spiders much larger than themselves using their strong silk.
Seasonal Activity
Active year-round indoors, but most frequently sighted in late summer and autumn when males wander in search of mates.
Description
This is a Ground Spider known for its 'mousy' velvety texture. Unlike many house spiders that sit in webs, this species is an athletic nomad that explores walls and floors at night. While its large size can be intimidating, it is a beneficial predator of indoor pests.
Key Features
Velvety grey abdomen, prominent cylindrical spinnerets, dark reddish-brown cephalothorax, and a lack of abdominal patterns.
Similar Species
May be confused with Wolf Spiders (Lycosidae), but lacks the two large primary eyes. It is often confused with the Australian Mouse Spider (Missulena), which is a much bulkier, more dangerous mygalomorph spider.
Life Cycle
Females lay eggs in a papery, white silk sac protected within their retreat. Spiderlings emerge and disperse. They typically live for 1–2 years.
Ecological Importance
Provides excellent natural pest control within the home, predating on silverfish, flies, and smaller spiders.
Conservation Status
Not evaluated (Common/Stable). It is a highly successful synanthropic species (thrives around humans).
Interesting Facts
The name 'Mouse Spider' comes from the way the spider moves with short, quick darting bursts, and the soft grey fur-like hair on its abdomen.
Photography Tips
To identify this species, clear shots of the spinnerets at the tail end and the eye arrangement on the head are most helpful.
Identified: 2026-05-21T01:42:26.418339