Spiders are arachnids. They have eight legs (compared to the six legs of insects) and up to eight eyes. Spiders also have spinnerets on their abdomen. These organs emit the silk that spiders use to make their webs and nests.

Spiders are predators and are categorized by how they hunt for food. They either spin webs to catch prey, actively hunt or stalk prey, ambush prey, or make burrows or holes in the ground to trap prey.

Spiders mostly prey on other bugs. A spider injects venom into its catch through fangs near its mouth to kill the bug, and it also may wrap the bug in silk to immobilize it. The venom contains digestive enzymes that break down the prey’s tissue, allowing the spider to suck up the digested goop.

Spiders reproduce by laying eggs, which they wrap in silk to form egg sacs. The sacs may look like little balls of white- or brown-coloured cotton and often are seen in the corners of ceilings, outdoor porches and overhangs. Some spiders carry their egg sacs. On average, an egg sac contains 250 eggs.

Spiders live year-round indoors. Outside, adult spiders die when freezing weather arrives, while juvenile spiders ride out the cold in a state dormancy to emerge in the spring.

Should I kill spiders?

Consider the following when deciding whether to kill spiders in and on your property:

• Your comfort level – Some people mildly dislike spiders; others have an irrational fear of spiders, which is called arachnophobia. Your level of comfort will determine how many spiders you can tolerate, if any, in your living space or commercial property.

• The threat level – While spiders for the most part are beneficial creatures, some have toxic venom that can make you ill if you get bit. Keep reading to learn how to identify common spiders and dangerous spiders in Canada.

• The nuisance factor - Spiders don’t transmit disease, contaminate food or destroy structures, but they poop a lot and their black and white feces is unsightly and hard to clean up. Plus, their webs, egg sacs and nests catch leaves and debris and generally look creepy. While one spider web may not be a problem, having an entire porch, storefront, dock or boat covered in webs and spider poop is not a pleasant experience.

Why are spiders in my house?

Spiders are in your house, store or cottage because they are hunting the bugs living inside. Spiders also may hunt for prey and live on building exteriors and boat docks.

Some structures are more likely to attract the prey on which spiders feed. These include homes and cottages located in the woods and near water, where flies and mosquitoes are plentiful. Crawling and flying insects also are attracted to damp basements and outdoor lights, which homes and commercial properties may keep on overnight.

When is spider season in Canada?

In Canada, spiders are most active in spring and summer or from about April through September. In late summer, spiders are most noticeable because they’ve grown to adult size. This also is when web-making spiders lay eggs in egg sacs, which can be seen in the corners of ceilings, porches and overhangs. In fall, spiders that actively hunt or stalk their prey may move indoors for warmth.

Do spiders bite?

Spiders do bite. They rarely bite humans, however. People often think they’ve been bit by a spider when they get an unexplained red mark on their skin, but usually this mark is caused by something else.

Spiders will bite to defend themselves. This might occur if you surprise them by reaching into a box or under the sofa where they are nesting, or by putting on shoes, clothing or garden gloves in which a spider is trapped. The bite of some spiders will feel like a bee sting.

The venomous black widow spider, found occasionally in southern Canada, poses a higher risk to humans. The bite of this spider affects the nervous system and causes pain, burning, swelling, and redness at the bite site. The bite of a black widow spider may affect some people more than others, but it is rarely fatal.

What are the common spiders and dangerous spiders in Canada?

More than 3,700 species of spiders live in North America. The 6 most common spiders and 1 occasionally dangerous spider in Canada are as follows:

• Cellar Spiders – Cellar spiders are found in the corners of basements, garages, barns and sheds. They are pale brown to yellow to gray in colour, have small oblong bodies (7 to 8 mm) and very long legs, which may increase their entire size sixfold. Cellar spiders also are called “daddy long-legs.” The spiders hang belly-side-up in their webs, which look haphazardly made and without pattern.

• Wolf Spiders – Wolf spiders in Canada are active hunters with excellent vision. They are dark brown in colour and some have stripes on their heads. Wolf spider size can vary. They can grow as big as 1.5 inches (3.8 cm). They do not build webs. Typically, they are found outdoors stalking prey, but they may come indoors during the hunt and to escape cold weather.

• House Spiders – House spiders in Canada range in colour from greyish white to orange-ish brown to nearly black and have visible markings on their bodies. Bodies typically are 6 to 8 mm long, with their two front legs nearly three times longer. Common house spiders build untidy looking “cobwebs” in dark corners and attics, under furniture and in areas with little human activity.

• Fishing Spiders – Also called dock or wharf spiders, fishing spiders are found near shorelines and waterfront cottages. They are Canada’s largest native spider and reach up to 3 inches in length. Some female fishing spiders have grown as big as a human hand. Fishing spiders have two rows of eyes, striped legs, and are brownish gray in colour with dark brown and black markings. They can walk on water thanks to their widely spaced legs and water-repelling hairs. They eat insects and minnows.

• Yellow and Black Garden Spiders – This large, colorful spider has distinctive yellow and black markings on its abdomen. Its body can be up to 1 inch (28 mm) long and it has a leg span of 3 inches (76 mm). An orb weaver, this spider builds large circular webs with a white zig-zag pattern in sunny outdoor areas protected from the wind. You’ll often see the female spider sitting in the middle of the web, waiting for prey.

• Hobo Spiders – Hobo spiders are invasive spiders found mostly in western Canada. They live in dark, damp places like basements and garages. They nest in cracks and crevices, between boxes and behind furniture, building funnel-shaped webs. Hobo spiders are brownish in colour and up to 11 to 14 mm in length. The hobo spider bite was believed to be harmful to humans and cause necrosis, or death of tissue cells, but new research indicates that hobo spider venom in not toxic.

• Black Widow Spiders – Found occasionally in southern Canada, black widow spiders are venomous and potentially harmful to humans. The spiders are not aggressive but will bite to defend themselves. Bites cause pain, redness and swelling but rarely are fatal. The spider spins a small, haphazard web near the ground in garages and sheds, and under rocks, branches, building materials and overturned garden pots. It is shiny black in colour and has a red hourglass-shaped mark on the underside of its abdomen. Its two front legs are longer than its body.

How to get rid of spiders

To get rid of spiders, follow these 4 steps:

1. Eliminate the food source - Spiders are attracted to properties where their insect prey live. They will go elsewhere if there is nothing for them to eat. Change exterior lights to yellow lights that don’t attract flying insects. Adjust flood lights and indoor light timers so they don’t pull night-flying insects directly to the home or business. Seal cracks, crevices and broken screens that let insects (and spiders) get indoors.

2. Physical removal – Use a telescoping duster, a HEPA vacuum or broom to remove spiders, webs and egg sacs from indoor and outdoor areas. The more egg sacs you remove, the fewer spiders you’ll have in the future.

3. Eliminate potential nesting sites – Make spaces less hospitable to spiders. Tape up boxes and store them off the ground. Eliminate clutter in garages, sheds, attics, basements and crawlspaces. At commercial properties, replace vegetation around the exterior perimeter with an 18-inch-wide swath of gravel to eliminate spider (and spider prey) hiding places. Reduce humidity in basements and crawlspaces by improving ventilation.

4. Use the best pest control products for spiders – A combination of products can help eliminate spiders from your home, cottage or business:

• Diatomaceous earth (DE) or exterminator dust – This natural desiccant will kill spiders by drying them out. Apply it to cracks, crevices, corners and near outdoor lights where spiders are active using a duster. The spiders walk through the DE, which scratches the waxy outer layer of their exoskeleton. This causes the spider to dry out and die. Learn more about DE and how to apply it.

• Crawling insect traps – Placing traps placed behind furniture, among storage boxes, in garages and boat houses let you catch the crawling insects that spiders eat and the spiders that actively hunt, such wolf spiders and fishing spiders. Learn more about crawling insect traps and how to use them.

• Insecticide sprays – Repellent aerosols and sprays kill spiders on contact. Also apply them to exterior cracks and crevices where funnel-shaped spider webs exist to flush out spiders, which you then can squash with a putty knife. 

Read more:

Why do I have spiders?

How to get rid of spiders