Spider Identification Guide
Cellar Spider - Daddy Longlegs
One of the most common and immediately recognizable spiders in Ontario homes. The subject of one of the most persistent spider myths in popular culture.
The cellar spider is the long-legged, delicate, ceiling-corner spider you have seen your entire life. Commonly called daddy longlegs, it is one of the most widespread spiders in Ontario homes and one of the most immediately recognizable: a tiny body suspended in the middle of a wispy, irregular web by legs that seem impossibly long relative to its body.
The cellar spider is responsible for one of the most durable myths in popular culture: the claim that daddy longlegs are the most venomous spider in the world but cannot bite humans because their fangs are too small. This is false on both counts. Cellar spiders are not highly venomous - their venom has limited effect even on the insects they prey on - and they can technically bite, but their mouthparts are so small relative to human skin that they cannot deliver a meaningful bite in practice.
Cellar spiders are passive hunters. They build a permanent web and wait, vibrating their body rapidly when disturbed (a behaviour called "whirling" or "vibrating") - possibly to appear larger or to help them see a predator's location. They are completely harmless to humans and are, if anything, beneficial - feeding on other insects and spiders that enter your home.
In Ontario
Cellar spiders are one of the most abundant spider species in Ontario homes and are found in virtually every structure in the province. They favour cool, dark, humid environments - basements, crawl spaces, the undersides of staircases, and corners of ceilings are their preferred habitat.
Because they maintain the same web for extended periods, individual spiders can be found in the same corner for months. The webs accumulate dust and debris over time, which is why old cellar spider webs often look dirty or grey. They are year-round residents - cellar spiders do not have a meaningful outdoor population in Ontario and complete their entire life cycle indoors.
One distinctive behaviour: when a cellar spider captures prey, it does not eat it immediately. It wraps the prey in silk and stores it, consuming it later. Old webs often contain the dried husks of past meals, which adds to the unkempt appearance of their silk.
Frequently Asked Questions
Is the daddy longlegs really the most venomous spider in the world?
No. This is one of the most persistent myths in popular culture and it is false. Cellar spiders (Pholcidae) have venom, but it is not particularly potent - even relative to other spider species. The myth has been tested and debunked, including by MythBusters. Cellar spiders are harmless to humans.
Can cellar spiders bite?
In theory, yes - they have fangs. In practice, their mouthparts are very small and they are not inclined to bite. There are rare documented cases of cellar spider bites causing a brief mild burning sensation that resolves quickly. For all practical purposes, they cannot bite humans in any meaningful way.
Why are there so many daddy longlegs in my basement?
Cellar spiders thrive in cool, dark, humid environments - which describes most Ontario basements. They are year-round residents indoors and reproduce steadily. Because they stay in the same web location, populations accumulate over time. High indoor cellar spider numbers often indicate that your basement has other insect activity providing them a food source.
Should I leave cellar spiders alone?
From a pest management perspective, cellar spiders are harmless and do eat other insects. However, most homeowners find accumulated cobwebs unacceptable regardless of the species producing them. Spider Squad's perimeter treatment reduces the overall indoor spider population, including cellar spiders, by eliminating the food sources and entry points that sustain them.
What is the difference between a cellar spider and a harvestman?
Both are commonly called daddy longlegs, which causes significant confusion. A harvestman (order Opiliones) is not a spider at all - it has one body segment, no venom, and no silk. A cellar spider (Pholcidae) is a true spider with two body segments, venom glands, and silk. In Ontario homes, the long-legged creature in your basement is almost certainly a cellar spider, not a harvestman.
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