Hackledmesh Weaver, Cedar Spider
Callobius severus
Amaurobiidae (Hacklemesh Weavers), Order Araneae. Characterized by sturdy builds and non-sticky 'hackled' silk.
Physical Description
A robust spider with a glossy, dark cephalothorax (shiny front section) and a larger, somewhat fuzzy oval abdomen. They appear stout with thick, powerful legs.
Size Estimate
Body length 10-20mm; total leg span typically 30-50mm. This particular specimen appears to be a sub-adult or adult female.
Coloration & Markings
Deep reddish-brown to blackish-brown cephalothorax; the abdomen is usually a duller grey or brown with a faint, darker pattern (folium) or chevron markings down the center.
Web Type
Hackledmesh web. These webs are not sticky with glue; instead, they use 'cribellate' silk which is fuzzy and physically entangles prey limbs. Webs are usually found in crevices.
Eye Arrangement
Eight eyes arranged in two rows of four. The eyes are relatively small and dark, suited for detecting movement near the entrance of their retreats.
Leg Characteristics
Medium-length, stocky legs. Often the same color as the cephalothorax or slightly lighter; they lack prominent banding but feature fine sensors (trichobothria) for detecting vibrations.
Venom & Safety Information
Venom Information
Neurotoxic/cytotoxic enzymes designed for insects. While they possess venom to immobilize prey, it is not considered dangerous to humans.
Medical Significance
Low medical significance. Bites are rare and usually only occur if the spider is pressed against skin. Symptoms are typically limited to localized pain and swelling similar to a bee sting.
Safety Recommendations
Use gloves when moving woodpiles or rocks. If found indoors, they can be easily relocated using a cup and piece of paper. No professional pest control is usually necessary.
Habitat & Behavior
Habitat & Range
Common along the Pacific Coast of North America (British Columbia to California). They prefer damp, dark areas such as under logs, in woodpiles, or basement corners.
Behavior & Temperament
Nocturnal ambush hunters. They are generally shy and remain in retreats during the day. While they can be defensive if squeezed, they typically flee from human contact.
Diet & Prey
Generalist predators eating beetles, ants, crickets, and other spiders. They sense vibrations on their mesh silk and rush out to bite and drag prey inside.
Seasonal Activity
Most active in late summer and autumn when males wander in search of mates. They may be found indoors more frequently during rainy seasons.
Description
The Hackledmesh Weaver is a sturdy, dark-toned spider often mistaken for more dangerous species due to its size and glossy appearance. It is a master of structural vibration sensing.
Key Features
Glossy 'piano-key' finish on the cephalothorax, velvety abdomen, and the presence of a 'hackled' messy web rather than a symmetric orb web.
Similar Species
Often confused with the Lace-web spider (Amaurobius similis) or occasionally the False Widow (Steatoda grossa), which has a more bulbous, shiny abdomen.
Life Cycle
Females produce a silken egg sac within their retreat. They are known for 'matriphagy' in some related species, where spiderlings consume the mother to gain nutrients, though they typically live 1-2 years.
Ecological Importance
Critical for controlling ground-dwelling insect populations. They act as a natural pest control for wooden structures by eating termites and wood-boring beetles.
Conservation Status
Not evaluated by IUCN, but currently widespread and secure throughout its range.
Interesting Facts
The 'hackled' silk they produce is combed out using a specialized organ on their hind legs called a calamistrum, creating a Velcro-like texture that snags insect legs.
Photography Tips
Focus on the cephalothorax to capture the glossy texture and eye arrangement. Side-profile shots help distinguish the abdominal shape and leg thickness.
Identified: 2026-07-06T23:08:14.389056