Feather-legged Spider, American Cribellate Spider
Uloborus glomosus
Uloboridae (Hackled Orb-Weavers), Order Araneae
Physical Description
A small spider with a highly distinctive profile; the abdomen is humped or 'lobed' and often looks like a piece of debris. They lack venom glands entirely. Females possess specialized hairs called a calamistrum on their fourth pair of legs for combing silk.
Size Estimate
Body length 3-6mm for females, males are smaller (2-3mm). Leg span approximately 10-15mm.
Coloration & Markings
Varies from creamy white to dark brown or mottled grey. Often features a darker band across the humped portion of the abdomen. The legs are typically banded with light and dark segments.
Web Type
Horizontal or tilted orb web made of 'hackled' or 'fuzzy' silk. Unlike most orb-weavers, they do not use sticky glue droplets, but rather a dense mesh of dry, tangled silk that snags prey.
Eye Arrangement
Eight small eyes arranged in two rows of four; the eyes are not particularly prominent compared to hunting spiders.
Leg Characteristics
The first pair of legs is noticeably long and robust, often held straight forward. The tibiae of the first pair often have dense 'brushes' of hairs, giving them a feathered appearance.
Venom & Safety Information
Venom Information
Unique among spiders: they possess no venom glands or fangs capable of injecting venom. They are physically incapable of envenomation.
Medical Significance
Zero medical significance. They are completely harmless to humans and pets. A 'bite' is nearly impossible and would result in no chemical reaction.
Safety Recommendations
No safety precautions are necessary. These spiders are beneficial and safe to have around the home or garden. If removal is desired, they can be gently moved with a brush into a container.
Habitat & Behavior
Habitat & Range
Found throughout North America. Prefers shaded areas, woodlands, low-lying shrubs, and occasionally the eaves of buildings or inside greenhouses.
Behavior & Temperament
Extremely docile and non-aggressive. When disturbed, they often remain motionless to mimic a twig or piece of dirt. Because they lack venom, they rely on wrapping prey extensively in hundreds of meters of silk.
Diet & Prey
Small flying insects like gnats, fruit flies, and mosquitoes. They wrap prey so tightly in silk that the insect is crushed or smothered before being digested externally.
Seasonal Activity
Most active from late spring through early autumn. Often overwinter as juveniles in leaf litter or crevices.
Description
The Feather-legged spider is a master of camouflage and a taxonomic oddity. It is one of the few spiders in the world that does not use venom to kill its prey. Instead, it creates incredibly intricate webs of hackled silk that act like Velcro, then wraps its victims in a suffocating mummy-like shroud of silk. Its humped body and habit of resting with its front legs outstretched make it look more like a bit of dried leaf than a predator.
Key Features
Humped abdomen, feathered brushes on the front legs, horizontal orb web with fuzzy (non-sticky) silk, and a lack of venom.
Similar Species
May be confused with members of the Tetragnathidae family (Long-jawed orb-weavers) due to the resting posture, but the humped abdomen is diagnostic for Uloboridae.
Life Cycle
Females produce flat, papery, often star-shaped or 'stellate' egg sacs which they guard. Spiderlings emerge and may balloon to new locations. Adults are most common in summer.
Ecological Importance
Excellent for natural pest control of small dipterans (flies). They serve as a food source for larger spiders and birds.
Conservation Status
Not evaluated by IUCN, but considered common and stable throughout their range.
Interesting Facts
Uloborids are the only family of spiders that have entirely lost their venom glands through evolution. They compensate by producing a specialized type of silk from a plate called a cribellum, which creates a 'fuzzy' texture that traps insects mechanically.
Photography Tips
Focus on the profile to capture the abdominal hump. Use macro settings to highlight the 'feathers' on the front legs. Side-lighting helps reveal the texture of the hackled silk web.
Identified: 2026-06-15T10:37:09.874281