Spider identification
On docks, railings and the water side of a cottage the furrow orb weaver sits in among the bridge orb weavers and is usually counted as one of them. It is a close cousin, it behaves the same way, and it is one of the first spiders on the building in spring and the last to leave in fall.
Grey, tan or reddish brown, 6 to 14 mm in the body, with a dark leaf shaped mark with a scalloped or wavy edge down the back, on a pale abdomen. The legs are banded. The web is a round orb, usually smaller and lower than the bridge orb weaver's, built between a railing and a post, across a window corner or under a dock edge. By day the spider sits in a silk retreat in a corner or under a rail; at night it sits in the hub.
Docks, boathouses, railings, the lake side of homes and cottages, bridges, and along rivers, marshes and ditches. It needs flying insects over water, so it is rarely far from it.
One of the few orb weavers that stays active in cool weather. On buildings from April to November, heaviest in July and August. Adults and egg sacs overwinter in sheltered cracks.
Not a concern. It runs rather than bites and a bite would be no more than a small local mark. Most "spider bites" in Ontario are never confirmed; see the bite section of our guide to common spiders in Ontario for what a real one looks like.
We treat it exactly as we treat the bridge orb weaver: webs, spiders and egg sacs vacuumed off every reachable surface, railings and dock edges included, with the high eaves swept by pole. Where the same corner refills we apply a targeted treatment to that site. Because it is active so early and late, lakeside homes see the benefit of the May and September visits on the Season Plan more than most. Every visit ends with a written summary of what we found and where product was applied, if any. Our spider control service and 60 day guarantee pages have the details and pricing.
Bridge orb weaver, Cross orb weaver, Common house spider. The bridge orb weaver has a pale cross rather than a scalloped leaf and is usually the more numerous of the two on a lakeside wall. The cross orb weaver is larger, sits in the web by day, and has the white cross. The common house spider builds a tangle, not an orb. The full list with photos is in the common spiders in Ontario guide.
Good to know
They are two species in the same genus and they live side by side. For control it does not matter which you have; both are lakeside orb weavers and both respond to removal and the same targeted treatment.
The furrow orb weaver overwinters as an adult and comes out with the first warm days, well before most other spiders. Early webs on docks and railings are usually this species.
No. The webs and the dark spotting are cosmetic. The spotting is droppings. It usually washes off, but left for a season in the sun it can mark light surfaces, which is one more reason for the spring visit.
Related guides: When is spider season along Lake Huron, Spiders near Lake Huron in Sarnia and Point Edward. Service areas where this spider is found: Bayfield, Goderich, Sarnia and Bright's Grove, Port Elgin.
