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image of a spider

General Facts

Although they often inspire feelings of fear or dread, spiders are beneficial. They prey on other pests, such as aphids, caterpillars, and various insects. The arachnids are typically nocturnal and react to confrontation by fleeing in most cases. Unlike other common pests, spiders are not known to transmit diseases to humans, but they do bite humans if provoked, and the venom of some species is highly toxic. However, the eight-legged arthropods commonly enter homes, where they spin webs and alarm people with their presence. Furthermore, spiders will bite on rare occasions.

Appearance / Identification

Despite being remarkably varied in appearance, spiders share a number of common characteristics that make basic identification easy. Most notably, all spiders have four pairs of legs, which are segmented and in most cases skinny in appearance. Unlike insects, which are comprised of three distinct body segments, spiders are arachnids and have unregimented bodies with two main divisions. The front portion called the cephalothorax, which is a fusion of the head and thorax, includes the spider’s eyes, mouth, fangs, poison glands, and stomach. The legs also attach to this area. The bulbous rear portion, which comprises the abdomen, houses vital organs and is essential to silk-spinning and mating. Most spiders found in Canada range from 3 to 8 mm in length, with males remaining much smaller in size than females.


Opportunistic and adaptable, spiders can be found in just about any habitat and thrive outdoors as well as indoors. The arachnids generally prefer dark, moist environments and tend to avoid contact with other organisms. In nature, spiders make homes in caves, tree hollows and shrubs, under rocks, and in soil. Manmade structures, such as homes, office buildings, and sheds, provide excellent shelter for the pests, as well. In manmade structures, spiders tend to build webs in basements and corners of rooms.


Spiders are predatory animals that feed on the living creatures they capture. Most spiders prey on insects or other spiders. Some larger species also eat small vertebrates, such as lizards, frogs, and birds. While most spiders are generalist predators that will eat just about any kind of prey they catch, some species are specialist feeders that only target one type of prey in their habitat.

Life Cycle / Reproduction

Most spiders lead solitary lives, though males and females will convene to mate during the spring and summer months. After mating, female spiders lay eggs in egg sacs, which are spun from their silk and usually contain thousands of tiny eggs. Females may hide the pouches or carry them until the eggs hatch. Hatching and development usually takes a few weeks. When the small spiderlings emerge from the egg sac, they either feed on food supplies provided by the mother or leave to find food on their own. Depending on the species, spiderlings may disperse by crawling or by ballooning, which involves releasing a length of silk and letting the wind spread the young to new territories. Because spiders have exoskeletons, the young must shed their skins several times until they reach adulthood. Most spiders live for about a year; however, some species may live as long as 15 years.

Problems Caused by Spiders

In rare instances, some species of spiders will bite humans. Bites typically result from the victim putting on a shoe or piece of clothing with a spider trapped inside. The widow spider (Latrodectus spp.) is the only spider found in Canada that can be hazardous to humans. Contrary to popular belief, black widow spider bites rarely result in death. Symptoms depend on the bite area, victim sensitivity, and amount of venom injected. The neurotoxins in the venom of the black widow affect the nervous system and may result in muscle cramps, sweating, headache, and high blood pressure. If left untreated, the bite site can become seriously infected. However, black widow spiders are not very common in Canada.

Aside from physical harm, spiders can cause psychological distress to individuals with arachnophobia. The sight of spiders can also affect the aesthetic of a home or building, as webs and crawling pests are unsightly. Though more of a nuisance than a hazard, the presence of spiders often strikes people as intolerable and worthy of eradication.

Detection / Signs of Infestation

Webs are a prime indication of the presence of spiders living in the home, while actually seeing the arachnids crawling around the residence is the biggest sign of a spider infestation. The pests are commonly found crawling or resting on ceilings and can occasionally be seen traversing table surfaces or floors. Shed skins and egg sacs in the residence are further signs of spider infestations.

Prevention Tips

As spiders primarily enter the home through gaps and openings around the residence, homeowners should keep windows and doors closed and properly sealed, and caulk any gaps in foundational walls. Keeping the residence clean and free from insects will also discourage spiders from entering by forcing them to look elsewhere for food sources. The frequent removal of webs also curbs spider infestations. Most spiders in the home prefer dark, moist environments, such as basements. Dehumidifiers may make the habitat less appealing to the pests, while removing clutter will cut down on the amount of hiding spaces spiders can take advantage of. Continually finding excess numbers of spiders in the home may signal a serious infestation issue requiring the services of a pest control specialist.

Main Types of Spiders in Canada

Common spiders found in Canadian households include the house spider, wolf spider, cellar spider, and fishing spider. Each of the main types of spiders in Canada is typically found in basements, garages, gardens, and similar locations.

Wolf spiders

wolf spider

Wolf spiders hunt for their prey instead of spinning webs and waiting. These spiders can be as large as 3 cm (just over 1 inch) in length and have a dark brown colour. Wolf spiders are usually found on the ground in grasslands, woodland floors, beaches and gardens. They mostly feed on insects. They are most likely to enter homes and buildings in the fall as they look for warm places for shelter.

Fishing spiders

fishing spider

Fishing spiders may look similar to wolf spiders but they have a different eye pattern. The adults can reach up to 7.5 cm (3 inches) in width. They are typically found near cottages and waterfronts, especially around rocks near the shoreline. These spiders forage for their prey. Unlike wolf spiders, which carry their egg sac behind their body, fishing spiders carry their egg sac under their head and front thorax (upper body).

Cellar spiders

cellar spider

Cellar spiders have very long legs and build their webs in the corners of cellars or cool and damp basements. Common names for cellar spiders include “daddy longlegs” and “skull spider”. The legs of these spiders are about five to six times longer than the length of their bodies. Female spiders may have a leg span reaching as much as seven centimeters, and males are slightly smaller.

Cellar spiders can be confused with another spider-like relative commonly known as the harvestman or daddy longlegs. The harvestman does not have two distinct body parts like true spiders, nor do they have silk-producing glands. However, with their four pairs of long slender legs, they may look like spiders at first glance.

House spiders

house spider

The house spider is commonly found within the house. The house spider varies in colour from dirty white to nearly black, with visible markings on its body. Its first pair of legs is almost three times the length of its whole body. It builds webs in dark corners, under furniture and anywhere insects might be caught.

Black Widow spiders

black widowspider

There are a few black widow species that can be found in Canada, mainly in the southern parts of the country, but they are not common. It is shiny black, with a distinctive red hourglass-shaped mark on the underside of its stomach. It spins a small, silk web close to the ground and is found in secluded places like garages and sheds, or under rocks or fallen trees when outside. It is not aggressive and prefers fleeing when disturbed, so it will only bite to defend itself.
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Black Widow spiders

Cellar spiders

Cobweb spiders

Dock spiders

Fishing spiders

House spiders

Jumping spiders