Feather-legged Orb-weaver, Feather-legged Spider
Uloborus glomosus
Uloboridae (Hackled Orb-weaver Spiders), Order Araneae. Key family trait: lacking venom glands.
Physical Description
Small spider featuring a distinctive hump-backed abdomen that is often taller than it is long. The abdomen typically has paired tufts of hairs. They possess a cribellum (a silk-spinning organ) that produces fuzzy, non-sticky hackled silk.
Size Estimate
Small; females are 3-6mm in body length, males 2-4mm. Leg span is typically under 15mm. This appears to be an adult female.
Coloration & Markings
Mottled brown, gray, and tan. The abdomen often has dark splotches or stripes. A key feature is the dark feather-like tufts of hair on the tibiae of the front legs.
Web Type
Horizontal or angled orb web made of fuzzy, non-sticky cribellate silk. Unlike most orb webs, these lack adhesive droplets, relying on the physical structure of the silk to snag prey.
Eye Arrangement
Eight small eyes arranged in two rows, though they are difficult to see without magnification. The arrangement is typical of Uloboridae, adapted for movement detection in the web.
Leg Characteristics
The first pair of legs is significantly longer and thicker than the others. The front legs feature prominent tufts of hairs (setae) on the tibiae, giving them a 'feathered' appearance.
Venom & Safety Information
Venom Information
Unique among spiders: Members of the Uloboridae family completely lack venom glands. They have no chemical means of incapacitating prey.
Medical Significance
None. They are completely harmless to humans and pets as they cannot produce venom.
Safety Recommendations
No safety measures needed. They are beneficial and harmless. If you wish to move one, gently use a piece of paper or a cup to relocate it to a shrub.
Habitat & Behavior
Habitat & Range
Found throughout North America. They prefer low vegetation, bushes, and shaded areas near buildings or in forests. They are commonly found in porches and eaves.
Behavior & Temperament
Extremely docile and non-aggressive. When disturbed, they may drop from the web or remain motionless to mimic a piece of debris or a dead leaf.
Diet & Prey
Small flying insects like flies and gnats. Because they lack venom, they wrap prey extensively in silk—sometimes hundreds of meters of it—to crush or immobilize the insect before using digestive enzymes.
Seasonal Activity
Most active from late spring through autumn. They are often seen in late summer when females are guarding egg sacs.
Description
The Feather-legged spider is a fascinating master of mimicry and silk-engineering. Often mistaken for a piece of dried leaf or detritus stuck in a web, it is actually a highly specialized hunter that relies on mechanical force rather than venom to secure its meals.
Key Features
Humped abdomen, feathered tufts on the front legs, horizontal orb web with fuzzy silk, and a lack of venom.
Similar Species
Other Uloborus species. It can be distinguished from typical Orb-weavers (Araneidae) by its fuzzy silk and front leg tufts.
Life Cycle
Females produce flat, papery, star-shaped or scalloped egg sacs that are light brown or gray. They often stay near the sac to guard it. Lifespan is generally one season/year.
Ecological Importance
Provides natural pest control for small nuisance insects (fungus gnats, fruit flies, midges) around homes and gardens.
Conservation Status
Not evaluated by IUCN, but currently widespread and common in its range with no major threats.
Interesting Facts
Uloborids are the only family of spiders that have entirely lost their venom glands through evolution. They rely on massive amounts of silk wrapping to compress and kill their prey.
Photography Tips
Focus on the front legs to capture the 'feather' tufts and the side profile to show the unique hump on the abdomen. Use a macro lens if possible due to their small size.
Identified: 2026-06-30T04:59:38.911340