Spider web types in BC: how to identify who built it

Why web type matters for management

Spiders have been building species-characteristic webs for 100 million years. The web design is as specific to the species as the spider's body plan — you can reliably identify the spider family from the web architecture, even if the spider itself is hiding. For pest management, this matters because it tells you what you're dealing with without requiring you to find, trap, and identify the spider. A large funnel web in your basement corner is a house spider. An irregular cobweb at ground level in your wood pile warrants a second look for black widows. An elaborate spiral web across your garden fence is an orb-weaver doing you ecological favours.

Cobwebs: the irregular tangle-web builders

When most people say 'cobweb,' they mean the irregular, tangled, apparently disorganised webs found in house corners, ceiling junctions, behind furniture, and in dark storage areas. In BC, cobwebs are built by two main groups: cellar spiders (Pholcus phalangioides) and false widows (Steatoda species). These are three-dimensional tangle webs — not flat, not spiral, but a disordered scaffold of silk anchored to multiple points, with a retreat area where the spider rests.

Cellar spider cobwebs are found predominantly on ceilings and upper walls, particularly in basements, bathrooms, and utility rooms. The spider hangs inverted in the web and vibrates rapidly when disturbed — this 'whirring' behaviour is the cellar spider's threat display. The webs accumulate debris over time and become more visible with age. Cellar spiders are completely harmless and beneficial — they actively hunt other spiders, including house spiders and false widows, which is why basements with cellar spiders often have lower populations of other species.

False widow cobwebs are typically found at lower levels: near the floor, in corners, under debris, in garages and outbuildings. Steatoda grossa and Steatoda nobilis (the two most common false widows in Metro Vancouver) build a similar tangle web that is structurally stronger than it looks — the silk has genuine tensile strength. The spider retreats into the upper part of the web when disturbed. Finding a messy but strong cobweb at floor level in a garage or shed, with a round-bodied dark spider retreating into the upper portion, is a false widow signature.

Funnel webs: the house spider signature

Funnel webs are the webs that European house spiders and giant house spiders build. The design is elegant and effective: a flat or slightly concave sheet of dense, non-sticky silk, with a funnel-shaped tube retreat at one end where the spider waits. When a prey insect lands on the sheet — disturbed by the silk trip-lines above it — the vibration alerts the spider, which rushes out, bites the prey, and drags it into the funnel to eat.

In Metro Vancouver basements, funnel webs are found in corners, in joist bays between floor joists, behind utility equipment, and in wall angles. The funnel entrance is typically 10–20 mm wide and 50–150 mm deep. In an occupied web, the silk sheet is clean and taut. In an abandoned web, the sheet fills with debris and loses tension. An active funnel web is a sign of a living house spider — usually female, potentially long-lived (up to 7 years). A collection of dusty, debris-filled funnel webs suggests a previous-season occupation that has been vacated.

Orb webs: the garden architects

The classic circular spider web — the one that shows up in children's drawings and Halloween decorations — is the orb web, built by spiders in the family Araneidae. In Metro Vancouver, the primary orb-weaver is the cross orb-weaver (Araneus diadematus), an introduced European species that is now completely ubiquitous in BC gardens. Large orb-weavers in other genera (Argiope, Larinioides) are also present.

An orb web is a mathematical marvel: radial spokes extending from a central hub, connected by a spiral of sticky capture silk. The spacing of the spiral increases from centre to edge, optimising the web's ability to intercept insects of varying sizes. A mature female Araneus diadematus builds a fresh web each night, consuming the previous night's web and re-spinning the silk. The web is typically oriented vertically, spanning open spaces between structural supports. A large, clean, taut orb web in morning light is an active web occupied by a resting spider somewhere in the foliage nearby.

Sheet webs: the ground-level network

Sheet webs are built by spiders in the family Linyphiidae — the 'money spiders' of folklore. They're thin, flat, horizontal platforms of non-sticky silk, often with vertical threads above and below anchoring the sheet. Flying and crawling insects blunder into the vertical threads and fall onto the sheet, where the spider (hiding underneath) grabs them through the silk. Sheet webs are found in grass, low vegetation, leaf litter, and ground-level vegetation.

In Metro Vancouver gardens, sheet webs are most visible in early morning on dewy days when they cover lawns and low shrubs in a network of interlocking platforms. This is sometimes alarming to homeowners who haven't noticed them before — but the spiders building them are all tiny (most linyphiid spiders are 1–5 mm) and completely harmless. A lawn covered in dewy sheet webs in autumn indicates a healthy population of beneficial predators.