Hackledmesh Weaver
Callobius severus
Amaurobiidae (Hackledmesh Weavers), Order Araneae
Physical Description
Robust body with a dark brown to blackish cephalothorax and abdomen. It has a slightly flattened carapace, stout legs, and distinct spinnerets visible at the posterior end of the abdomen.
Size Estimate
Body length ranges from 10 to 18 mm, with a leg span up to 35 mm. This specimen appears to be an adult.
Coloration & Markings
Dark reddish-brown to black overall coloration. The abdomen often features a faint, lighter chevron or mottled pattern, though it can appear solid dark depending on lighting and age.
Web Type
Cribellate sheet web or funnel-like retreat connected to a messy silk mat, usually built near ground level in dark, damp spaces.
Eye Arrangement
Eight eyes arranged in two rows of four, typical for cribellate spiders, with a relatively compact ocular area on the front of the carapace.
Leg Characteristics
Stout, moderately long legs with dense spines. The fourth pair of legs possesses a specialized combing structure called a calamistrum used to comb cribellate silk.
Venom & Safety Information
Venom Information
Contains mild venom used to subdue invertebrate prey. It is not considered dangerous or medically significant to humans.
Medical Significance
Harmless to humans. A bite may cause minor, temporary local discomfort or redness similar to a mild bee sting, but this is extremely rare.
Safety Recommendations
No special precautions needed beyond standard caution. If found indoors, gently guide the spider into a container using a piece of paper and release it outside.
Habitat & Behavior
Habitat & Range
Found primarily in the Pacific Northwest of North America, inhabiting damp forests, under logs, bark, rocks, and occasionally wandering into houses during autumn.
Behavior & Temperament
Nervous and fast-moving when disturbed, though generally non-aggressive. They spend most of their time hidden inside their silk retreats and hunt at night.
Diet & Prey
Generalist predators feeding on crawling insects such as beetles, ants, roaches, and woodlice trapped near their ground-level webs.
Seasonal Activity
Most commonly seen in late summer and autumn when mature males wander extensively in search of females, frequently entering human dwellings.
Description
Callobius severus is a striking, robust ground-dwelling spider commonly encountered in Pacific Northwest woodlands and occasionally basements. Known for building messy cribellate webs close to the ground, this dark-colored spider plays an important role in controlling forest floor insect populations.
Key Features
Robust dark reddish-brown body, presence of a cribellum and calamistrum, ground-dwelling habit, and characteristic messy sheet/funnel webs in damp areas.
Similar Species
Can be confused with funnel-web grass spiders (Agelenidae) or hackledmesh spiders of the genus Coras, distinguished primarily by eye arrangement and the presence of the cribellum.
Life Cycle
Females construct silken egg sacs in sheltered retreats and guard them. Spiderlings hatch, disperse locally, and mature over one to two years through multiple molts.
Ecological Importance
Serves as an effective predator of forest floor invertebrates, helping regulate insect populations and acting as a food source for small mammals and birds.
Conservation Status
Not evaluated by the IUCN, but populations are secure and widespread throughout its native range.
Interesting Facts
These spiders use cribellate silk, which consists of extremely fine, woolly nanofibres combed by the calamistrum rather than being coated in sticky glue droplets.
Photography Tips
Use a macro lens in natural or diffused lighting. Capture dorsal views to show markings and close-ups of the eye region and spinnerets for accurate identification.
Identified: 2026-09-03T15:24:58.702550