Mouse Spider (European), Stealthy Ground Spider
Scotophaeus blackwalli
Gnaphosidae (Ground Spiders), Order Araneae
Physical Description
A medium-sized spider with a robust, flattened cephalothorax and an elongated, oval abdomen. The body is covered in fine, velvety hairs (setae) that give it a sheen reminiscent of mouse fur. It has very prominent, barrel-shaped spinnerets projecting from the rear of the abdomen, which is diagnostic of the Gnaphosidae family.
Size Estimate
Body length typically ranges from 8mm to 12mm (females being larger). Total leg span is approximately 20mm to 30mm. This specimen appears to be an adult.
Coloration & Markings
The cephalothorax is dark brown to reddish-brown. The abdomen is typically a uniform mousy-grey, silvery-grey, or drab brown with no distinct patterns, though it may have a slight metallic sheen under direct light.
Web Type
This is a hunting spider that does not build a traditional capture web. Instead, it spins a small, silk 'retreat' or tubular sac in crevices to rest during the day or to molt.
Eye Arrangement
8 eyes in two slightly curved rows of four. The posterior median eyes are often oval or irregular in shape rather than perfectly circular, which is a characteristic used by specialists to identify ground spiders.
Leg Characteristics
The legs are relatively short, sturdy, and well-proportioned for sprinting. They are same color as the cephalothorax and covered in fine hairs. When at rest, they often keep their legs slightly spread.
Venom & Safety Information
Venom Information
Possesses a mild venom used to subdue small insects. It is not considered toxic to humans.
Medical Significance
Low medical significance. Bites are rare and usually only occur if the spider is pinched or squeezed. Symptoms are generally limited to mild localized pain, redness, or swelling similar to a bee sting.
Safety Recommendations
Harmless; no action is usually needed. If you wish to remove it, use the 'cup and paper' method to relocate it outside. To prevent them from entering, seal cracks around windows and doors.
Habitat & Behavior
Habitat & Range
Commonly found in and around human dwellings (synanthropic). Native to Europe but widely introduced to North America (especially the West Coast) and parts of the Southern Hemisphere. Often found behind curtains, under furniture, or on walls at night.
Behavior & Temperament
A nocturnal, active hunter. They are exceptionally fast and 'stealthy,' moving with sudden bursts of speed. They are generally non-aggressive toward humans and will attempt to flee rather than bite when disturbed.
Diet & Prey
They hunt other insects and are known for their prowess in hunting other spiders, including some larger than themselves. They use their strong silk to 'tack' down prey during a struggle.
Seasonal Activity
Visible year-round indoors, but most active and frequently spotted in late summer and autumn when males wander in search of mates.
Description
The Mouse Spider is a common but often misunderstood nocturnal visitor in homes. Named for its scurrying gait and velvet-grey abdomen, it is a master of the vertical world, easily navigating walls and ceilings in search of pests. Rather than building webs to trap food, it relies on speed and strength to overpower its prey.
Key Features
Velvety grey abdomen with a mouse-like sheen; prominent, tube-like spinnerets at the rear; cephalothorax darker than the abdomen; fast scurrying movement.
Similar Species
Often confused with the 'Mouse Spider' of Australia (Missulena), which is a heavy-bodied mygalomorph and much more dangerous. Also similar to other Ground Spiders (Herpyllus ecclesiasticus/Parsons Spider) which have distinct white markings.
Life Cycle
Females lay eggs in a flattened, papery white silk sac hidden in a crevice. They show some level of maternal guarding of the sac until the spiderlings emerge. They typically live for 1 to 2 years.
Ecological Importance
Highly beneficial as a natural pest controller. They keep populations of indoor insects and other spiders in check without the use of webs that mess up the home.
Conservation Status
Not evaluated by the IUCN, but considered common and widespread with stable populations in urban environments.
Interesting Facts
The name 'Mouse Spider' refers to the appearance of its abdominal hair, not its size or diet. They have a unique 'silk-tacking' strategy where they rapidly circle large prey while sticking them to the substrate with thick silk lines.
Photography Tips
Since they are nocturnal, use a diffused flash to capture the texture of the abdominal hairs. Side-profile shots are best for showing the diagnostic spinnerets.
Identified: 2026-07-17T07:01:18.949598