Cobweb Spider

Cobweb spiders is a broad common name applied to members of the family Theridiidae that build the classic irregular, tangled silk structure most people picture when they hear the word cobweb. The genus Steatoda, sometimes called false widow spiders for their resemblance to true widow spiders, is among the most familiar cobweb-spinning groups found around homes and gardens worldwide.

Unlike the neat, geometric spiral of an orb weaver, a cobweb spider's web is a chaotic three-dimensional scaffold of crisscrossing threads, often anchored in a corner where a wall meets the ceiling or floor. Some threads run down to the ground and are coated with sticky droplets, acting as trip lines that snap taut and hoist a walking insect up into the tangle when it brushes against one.

Cobweb spiders are shy and sedentary, generally remaining in or near their web and retreating rather than confronting anything larger than typical prey. Their webs, once established, are rarely rebuilt from scratch but instead continuously repaired and added to over the spider's lifetime.

• Rounded, bulbous abdomen, often glossy brown, purplish-brown, or patterned with pale markings
• Legs relatively short compared to the body, suited to moving through a dense tangle of silk
• Web is an irregular, multi-layered tangle rather than a flat spiral, usually built in a sheltered corner
• Gumfoot threads run from the web down to the substrate, tipped with sticky silk to snag walking insects
• Spider typically hangs upside down within the tangle, retreating to a hidden crevice when disturbed
• Lookalikes include true widow spiders, but cobweb spiders in general lack the widows' bold red or orange hourglass marking

Cobweb spiders are found nearly worldwide in sheltered, undisturbed spaces: corners of garages, sheds, basements, window frames, woodpiles, and garden structures. They tolerate both indoor and outdoor conditions and are active year-round in heated buildings, while outdoor populations are most noticeable from summer through autumn in temperate climates.

These spiders wait motionless in their tangled web for insects such as flies, ants, beetles, and other small arthropods to become caught on the sticky gumfoot lines. Once prey is snagged, the spider quickly wraps it in silk and hoists it up into the web to feed. Cobweb spiders play a useful role in controlling small insect pests around structures, and their persistent, rarely-abandoned webs can accumulate significant amounts of debris and prey remains over time.

Females produce one or more round, papery egg sacs that are suspended within the web and guarded until the spiderlings emerge. Hatchlings disperse to build their own small webs nearby, growing through a series of molts over several months to a year. In temperate climates, cobweb spiders often overwinter as eggs, juveniles, or sheltered adults, resuming activity and web-building as temperatures warm.