Mouse Spider Identification Guide
Recognize the mouse spider by its glossy body, oversized jaws, and burrow entrance with a trapdoor-like lid.
Read the full Mouse Spider encyclopedia entry →
Key Visual Features
Mouse spiders are robust, burrowing spiders named for their fur-toned coloring on some body parts, reminiscent of a mouse's coat.
- Size: Body length roughly 10-30 mm, with females typically larger and bulkier than males.
- Color: Glossy black to dark brown carapace and legs; some species have a bluish tinge on the front of the head region, and males in particular may show a reddish or orange patch on the head.
- Body shape: Stocky and heavily built, with a broad, rounded abdomen and a wide, shiny cephalothorax.
- Jaws (chelicerae): Notably large and robust, often as wide as the head itself, pointing forward rather than downward.
- Eyes: Eight eyes clustered tightly together on a raised area at the front of the head.
- Legs: Eight thick, sturdy legs suited for digging rather than climbing.
Where and When You'd See It
Mouse spiders are burrowing spiders that dig vertical or slightly angled tunnels in soil, often lined with silk. The burrow entrance may have a thin silk-and-soil lid, similar to trapdoor spiders. Males are more likely to be seen wandering in the open, particularly after rain or during warm, humid evenings when they search for mates. Females rarely leave their burrows.
Similar-Looking Bugs
- Trapdoor spiders: Similar burrowing lifestyle and lid-covered entrance, but trapdoor spiders generally have smaller jaws relative to head size and a less glossy appearance.
- Funnel-web type spiders: Also glossy and dark, but typically have a funnel-shaped web entrance rather than a simple burrow, and a more elongated body.
- Wolf spiders: Do not build permanent lidded burrows and have a distinctive eye arrangement in three rows rather than a tight cluster.
Quick ID Checklist
- Glossy black to brown body with a stocky, robust build
- Oversized, forward-pointing jaws relative to head size
- Burrow with a thin silk-lined lid at the entrance
- Males wandering openly after rain, especially in the evening
- Eight eyes clustered together at the front of the head
Behavior Notes
These spiders spend the vast majority of their lives underground, ambushing prey that walks near the burrow entrance and retreating quickly if disturbed. Males leave their burrows permanently once mature to search for mates.
Frequently asked questions
How can I tell a mouse spider from a trapdoor spider?
Look at the jaws — mouse spiders have unusually large, forward-pointing jaws relative to head size, while trapdoor spiders have comparatively smaller jaws and a less glossy body.
Why are mouse spiders called 'mouse' spiders?
The name refers to the soft, fur-like coloring seen on parts of the body of some species, which was thought to resemble a mouse's coat.
When are mouse spiders most visible?
Wandering males are most often seen after rain or on warm, humid evenings when they leave their burrows to search for mates; females stay in their burrows almost permanently.
What does a mouse spider burrow look like?
It's typically a vertical or angled tunnel in soil with a thin silk-and-soil lid at the entrance, similar in concept to a trapdoor spider's burrow.