What are they?
Spiders commonly found in Canadian homes include house spiders, wolf spiders, cellar spiders, fishing spiders, and (much less often) black widow spiders. They are usually found in corners of rooms, closets, boxes, dark crevices, basements, garages, and gardens.
The spider has an unsegmented body with two main divisions and four pairs of walking legs. It also has organs for producing silk, which is used for making nests, webs to catch prey, or cocoons for its eggs.
Most spiders prey on insects, many of them pests. Once the prey becomes tangled in the web, the spider immobilizes it by wrapping it in more silk and then injecting venom to paralyze it. Later, the spider injects a predigestive liquid and sucks out all the nutrients from its prey. Not all spiders are web spinners, and there are many types of spiders that use different strategies to catch their food.
Types of spiders
Spiders can have up to eight eyes. With so many eyes, it is surprising that most spiders are near-sighted.
Wolf spiders are unusual because they do not build webs; instead, they hunt for their prey. These spiders can be as large as 3 cm (just over 1 inch) in length and are dark brown in colour. They are generally found on the ground in grasslands, woodland floors, beaches, and gardens. They mostly feed on insects. In the fall, they look for warm places, so they are more likely to enter our homes around that time.
Cellar spiders have very long legs and build their webs in the corners of cellars or cool, damp basements. Cellar spiders are harmless and can be controlled by removing the webs and reducing the humidity in that area of your house.
Cellar spiders have also been called daddy-long-leg spiders, and can be confused with another spider-like relative commonly known as the harvestman or daddy long-legs. The harvestman does not have two distinct body parts like true spiders, and it does not have silk-producing glands either. But it does have four pairs of long slender legs, which make it look like a spider at first glance.
House spiders and black widow spiders
The house and black widow spiders belong to the same family. The house spider is more commonly found within the house, whereas the black widow spider is more likely to be found in dark crawl spaces, garages, or outhouses. 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.
The black widow spider is rare in Canada, found mainly in southern regions along the Canada-United States border. 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.
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. If you are concerned about the potential presence of black widow spiders, be careful when working around spider webs in secluded areas, and wear protective gloves if needed.
Although fishing spiders look like wolf spiders, they have a different eye pattern. The adults can reach up to 7.5 cm (3 inches) in width. They are commonly found near cottages and waterfronts, especially around rocks near the shoreline. These spiders forage for their prey (insects, minnows, etc.). 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).
Should I be concerned?
Spiders are excellent pest control agents. Wolf spiders are especially helpful to farmers and gardeners because they prey on common crop pests like caterpillars, plant bugs, and aphids.
Spiders do not transmit any diseases. Although nearly all spiders have venom glands, they rarely bite humans, and only a few species (like the black widow spider) can have a venomous -- but not usually fatal -- bite. Most spiders are nocturnal, shy, and avoid conflict by running away. They will only bite if they feel threatened (for example, being squeezed or held).
The degree of reaction to the black widow spider bite depends on the area of the body bitten, amount of venom injected, and a person's sensitivity to the venom. Serious long-term complications or death are very rare. If bitten, remain calm, and immediately get medical attention (contact your doctor, hospital, or poison control center). Apply an ice pack directly to the bite area to relieve swelling and pain.
How can I get rid of spiders?
Keeping your house clean reduces the number of pests, which are food sources for spiders. To prevent pests from entering your home, weather strip or caulk windows and doors, and repair screens. When cleaning your garage or basement, or working in your garden, it is a good idea to wear gloves to avoid exposing yourself to unexpected spider bites. Spiders are generally beneficial: a few spiders left in your basement and crawlspaces will help to capture earwigs and other insects.
- Sweep or vacuum baseboards and corners of rooms often to remove any food crumbs.
- Remove spider webs when spiders are not in them.
- Sweep behind washers and dryers often and rearrange furniture once in a while to prevent spiders from spinning webs in the same place.
- Keep clothing, shoes, and blankets off the floor so that spiders do not hide in them during the day.
- If there is a spider near a door or window, chase it outside with a soft brush.
- You can also trap live spiders with a glass jar and a piece of stiff paper and then release them outdoors.
- If needed, spiders can be killed by using a fly swatter, rolled-up paper, or magazine.
- Use yellow light bulbs outdoors to attract fewer insects, which will discourage spiders from spinning webs near your house.
- If you have an outhouse, always check to make sure there are no spiders underneath the rim of the seat. Make sure that the outhouse is clean, the door is weather stripped and closes tightly, and all openings are screened properly.
If you use a pesticide to control your pest problem, read the label to make sure you are choosing the right product for the right pest. Follow all label directions and warnings carefully. Always look for a Pest Control Products (PCP) number on the label so you know the product has been approved by Health Canada. See Use pesticides safely for more information on using pesticides safely
Complete removal of spiders using chemicals is not recommended, because spiders are natural and efficient pest control agents.
If the infestation in your house or garden is bad enough that you need to use pesticides, you can buy registered products in hardware stores and garden centres to control most common spiders. They can be applied around the exterior surfaces of window and door frames to prevent entry. There are also products that can be sprayed or painted on interior window and door frames, baseboards, floors, floor coverings, underneath furniture, and in closets and crevices.
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