Canada is home to a diverse array of spider species. These arachnids are an integral part of its ecosystems, contributing to ecological balance.
Spiders Across Canada
Spiders are widely distributed throughout Canada, inhabiting every province and territory, from dense forests to urban environments. Over 1,400 different species have been identified within Canada’s borders.
These arachnids serve as natural pest controllers, preying on various insects and other small invertebrates. Their dietary habits help regulate insect populations, benefiting agricultural areas and natural ecosystems.
Frequently Encountered Spiders
Many spider species commonly encountered in Canadian homes and gardens are generally harmless to humans. The common house spider (Parasteatoda tepidariorum) often builds irregular webs in corners and is light brown with markings on its abdomen. Cellar spiders (Pholcus phalangioides), also known as daddy long-legs, have very long, thin legs and construct loose, messy webs in damp, dark areas. Both species primarily feed on insects, and their bites are rare, causing only minor, localized reactions if they occur.
Jumping spiders (family Salticidae) are another frequently observed group, characterized by their compact bodies, short legs, and excellent eyesight. They do not build webs for prey capture but instead actively hunt during the day, ambushing insects with a sudden pounce. Garden spiders (family Araneidae), like the orb weavers, create intricate, circular webs in gardens and fields. These spiders are colorful and larger in size, yet their bites are uncommon and mild, often compared to a bee sting.
Spiders of Medical Interest
While most Canadian spiders are not considered dangerous, a few species possess venom that can be medically significant to humans. The Western Black Widow (Latrodectus hesperus) is one such spider, primarily found in the warmer, drier regions of western Canada, including southern British Columbia, Alberta, Saskatchewan, and Manitoba. Females are glossy black with a distinct red hourglass marking on the underside of their abdomen, while males are smaller and lighter in color with less prominent markings. They prefer dark, secluded areas such as woodpiles, sheds, and under rocks.
The venom of the Western Black Widow is neurotoxic, affecting the nervous system. A bite can cause symptoms such as localized pain, muscle cramps, nausea, sweating, and abdominal pain, though fatalities are exceedingly rare. While the brown recluse spider (Loxosceles reclusa) is often a concern, it is not native to Canada, and confirmed sightings are exceptionally rare, usually involving spiders transported accidentally in goods. Its venom is cytotoxic, potentially causing tissue damage. If a bite from any spider is suspected to be from a medically significant species, or if severe symptoms develop, seeking immediate medical attention is advisable.