Noble False Widow
Steatoda nobilis
Family Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with a glossy, bulbous abdomen and a smaller cephalothorax. The abdomen is typically dark and oval-shaped with a distinct waxy texture. Females are significantly larger and more robust than males, possessing a classic 'widow' shape but lacking the red hourglass.
Size Estimate
Female body length 9.5-14mm, leg span up to 25-30mm. Male body length 7-11mm. This specimen appears to be a mature or near-mature female.
Coloration & Markings
Dark reddish-brown to blackish-brown base. The most distinguishing feature is a cream or pale-yellow 'pentagon' or 'skull' shaped marking on the dorsal side of the abdomen, often outlined by a darker line. There is often a white band around the front of the abdomen.
Web Type
Builds a three-dimensional scaffold or 'tangle' web, typically in a corner or crevice. The web is made of very strong, non-sticky silk that crackles when torn. It often leads into a tubular retreat where the spider hides during the day.
Eye Arrangement
Consists of eight eyes in two rows. The eyes are small and relatively equal in size, typical of the Theridiidae family which relies more on web vibrations than keen eyesight.
Leg Characteristics
Legs are glossy, reddish-brown, and moderately long. They lack heavy spination but have fine hairs. In some light, the legs may show faint dark banding at the joints.
Venom & Safety Information
Venom Information
Neurotoxic venom. It is considered the most venomous spider in the UK, but its potency is much lower than true widows (Latrodectus). The venom contains alpha-latrotoxin, which affects the nervous system.
Medical Significance
Low to Moderate. Bites are rare and usually happen when the spider is caught in clothing. Symptoms are comparable to a wasp sting: localized pain, swelling, and occasionally minor malaise or lethargy. It is not lethal to healthy humans.
Safety Recommendations
If found in a crevice outside, it is best left alone as it provides free pest control. If it must be moved, use the 'cup and card' method. Avoid handling with bare hands. In the rare event of a bite, apply a cold compress and seek medical attention only if an allergic reaction occurs.
Habitat & Behavior
Habitat & Range
Originating from Madeira and the Canary Islands; now widely invasive in Western Europe, the UK, and parts of the United States (specifically coastal California). It prefers man-made structures, walls, window frames, and garden sheds.
Behavior & Temperament
A reclusive, nocturnal ambush hunter. It stays in its retreat during the day and moves to the edge of the web at night. It is not aggressive and will usually retreat further into its hole if disturbed; it only bites if squeezed or trapped against skin.
Diet & Prey
Feeds primarily on crawling and flying insects such as flies, moths, and beetles. Due to its strong silk, it can occasionally overpower larger prey including other spiders and small woodlice.
Seasonal Activity
Active year-round in warmer climates or indoors. Outdoors, peak activity and mating occur during the late summer and autumn (August to October).
Description
The Noble False Widow is a striking and often misunderstood arachnid. Often mistaken for more dangerous relatives, it is distinguished by its glossy chocolate-brown body and the 'skull-like' pattern on its back. It is a master of architectural silk-spinning, creating complex tangle webs in the nooks and crannies of house exteriors.
Key Features
Glossy bulbous abdomen, cream 'skull' or 'church window' pattern on the dorsal abdomen, and reddish-brown legs. Absence of a red hourglass on the underside.
Similar Species
Steatoda grossa (Cupboard Spider), Steatoda bipunctata (Rabbit Hutch Spider), and Latrodectus species (True Widows). S. nobilis is distinguished by its specific dorsal pattern and larger size compared to other Steatoda.
Life Cycle
Females produce several spherical, cream-colored egg sacs throughout the year. Spiderlings emerge and disperse. They can live for several years (up to 5 for females), which is long for a temperate spider.
Ecological Importance
Acts as an effective predator of common household pests including flies and mosquitoes. However, as an invasive species in some areas, it may outcompete native spider species for food and nesting sites.
Conservation Status
Not evaluated. It is an expanding, invasive species in many parts of the world and is currently under no threat.
Interesting Facts
The Noble False Widow is an incredibly successful colonizer because it can produce egg sacs year-round in temperate climates and has a very high tolerance for varying temperatures compared to other tropical spiders.
Photography Tips
Focus on the dorsal (top) side of the abdomen to capture the 'skull' pattern. Use a flash to highlight the glossy texture of the cephalothorax, and try to get a side profile to show the body proportions.
User Notes
Found in a crevice hiding in a white wall out front of our house yesterday on the right side of our house in a web peeking partially
Identified: 2026-04-25T19:56:13.106459