Updated at: 21-09-2023 - By: petstutorial

Insects are an integral part of Canada’s diverse ecosystem, playing crucial roles in pollination, decomposition, and pest control. While most insects are harmless or even beneficial, some can pose a significant threat to humans and other animals.

In this article, we will explore the top 10 most dangerous insects in Canada, based on their potential to cause harm through bites, stings, or disease transmission.


Top 10 Most Dangerous Insects in Canada

Black Widow Spider



There are two species of black widow spider in Canadthe western black widow found in parts of British Columbia through to Manitoba (mostly restricted to areas close to the southern Canada-U.S. border) and the northern black widow in southern and eastern Ontario.

Black widow spiders (Latrodectus mactans and Latrodectus hesperus) are found throughout southern Canada, the United States, and Mexico.

The largest population of black widow spiders in Canada is found in Ontario.

Black widow spiders are typically found in the southern portions of the Canadian provinces, in areas near the U.S. border, due to their preference for warmer temperatures.

The female black widow spider is about 12 to 13mm in size (not including the legs), while the male is about half that size.

The female black widow has a red hourglass-shaped marking on the underside of its globular abdomen, while the male black widows have yellow, red, and white bands and spots over their backs, as do both sexes of black widows in their immature stages.

Black widows prefer to live in dark, undisturbed locations, and their messy, irregular-shaped webs are typically found under furniture or in the corners of basements and storage areas.

Black widow spiders tend to thrive in hot and humid conditions, which is why they are often found in the Okanagan Valley in British Columbia.

Black widow spiders are the only spiders in Canada that can harm humans to the point where medical attention is necessary, although they are generally timid and do not like to bite.

Brown Recluse Spider


The brown recluse spider (Loxosceles reclusa) is not native to Canada and is primarily found in the southern and central United States.

Brown recluse spiders are pale tan to brown, with uniformly colored, no-spine legs. The female bodies range in size from 10 to 15 millimeters, while males are generally half the size of females.

The most distinguishing feature of a brown recluse spider is a dark violin-shaped mark on its back, with the neck of the violin pointing toward the rear (abdomen) of the spider.

Brown recluse spiders are not aggressive and bites from the species are uncommon. Like most spiders, they typically only bite when disturbed, although it is possible to inadvertently threaten them.

Once established in a home, brown recluse spiders can be difficult to control as they take shelter in dry, dark, undisturbed areas, and many such places exist inside homes and buildings.

The venom of a brown recluse spider can sometimes cause serious wounds, although bites are rare. If you suspect a brown recluse spider infestation, it is best to contact a professional pest control service for treatment.

Hobo Spider

The hobo spider (Eratigena agrestis, formerly Tegenaria agrestis) is a member of the funnel web spider family, known for constructing funnel-shaped webs and lying in wait for prey insects to blunder onto their webs.

Hobo spiders are sometimes found in or around human habitations, as they can build their webs in almost any habitat containing holes, cracks, or crevices that can support tunnel formation.

These spiders are not naturally aggressive and would rather run away than bite. They may only become aggressive when catching prey or when trapped against a person’s skin.

Hobo spiders are light brown with pale markings and are about 1/2 to 5/8 inch in body length. Unlike typical agelenids, their webs are almost horizontal and not as messy.

While hobo spider bites have been considered dangerous in the past, new evidence suggests that they are not as harmful as once thought. Most spiders in the funnel web spider family are harmless or only cause minor bite reactions.

Male hobo spiders are often searching for females to mate with between July and September, which is when most hobo spider bites are suspected to occur.


Mosquitoes are approximately 3,600 species of small flies comprising the family Culicidae. The word “mosquito” is Spanish for “little fly”. They have a slender segmented body, one pair of wings, one pair of halteres, and three pairs of long, thin legs.

In Canada, there are over 80 species of mosquitoes, with the most common being the Aedes, Anopheles, and Culex species. These mosquitoes can be found in various habitats, including urban areas, forests, and wetlands.

Female mosquitoes feed on the blood of humans and animals, while both male and female mosquitoes feed on flower nectar and fruit juices. The female’s proboscis is designed to pierce the skin and suck blood, while the male’s proboscis is not strong enough to pierce the skin.

Mosquito bites can cause an itchy weal, a raised bump on the skin, due to the mosquito’s saliva being transferred during the bite. In addition to their irritating bites, mosquitoes can also transmit diseases. They are important vectors of parasitic diseases such as malaria and filariasis, and arboviral diseases such as yellow fever, Chikungunya, West Nile, dengue fever, and Zika.

To control mosquito populations and help prevent the spread of diseases, it is important to eliminate standing water where mosquitoes can breed. This includes removing sources of standing water such as buckets, tires, and potted plant trays. Using mosquito repellents and wearing protective clothing can also help reduce the risk of mosquito bites and the transmission of diseases.

Asian Giant Hornet

The Asian giant hornet, also known as the northern giant hornet or Japanese giant hornet, is the world’s largest hornet, native to temperate and tropical East Asia, South Asia, Mainland Southeast Asia, and parts of the Russian Far East.

In late 2019, it was discovered in the Pacific Northwest of North America, with a few more additional sightings in 2020 and nests found in 2021, raising concerns about its potential as an invasive species.

The scientific community has adopted the common name “northern giant hornet” for this species, while the media has popularized the nickname “murder hornet”.

Description and Characteristics
– The Asian giant hornet is known for its large size, with queens growing up to two inches long.
– It has a distinctive appearance, with a fierce face featuring teardrop eyes, orange and black stripes that extend down its body, and broad, wispy wings resembling those of a small dragonfly.
– These hornets have a yellow to orange head and a black thorax.

Invasive Potential
– The discovery of Asian giant hornets in North America has raised concerns about their impact on local ecosystems and honeybee populations.
– The Washington State Department of Agriculture and other organizations have been working to track and control the spread of these hornets.
– In Canada, the hornets were first discovered in two locations in British Columbia in the fall of 2019.

Distinguishing from Other Insects
– The Asian giant hornet can be distinguished from other insects by its size, appearance, and behavior.
– Some insects that might be confused with the Asian giant hornet include the European hornet, southern yellowjacket, great golden digger wasp, carpenter bee, paper wasp, bald-faced hornet, hover fly, pigeon horntail, bee robber fly, and giant robber fly.


Ticks are parasitic arachnids that belong to the mite superorder Parasitiformes. They are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians.

Ticks are not insects but are closely related to spiders and mites. Here are some key points about ticks:

– Types of Ticks: There are two main groups of ticks: hard ticks and soft ticks. Hard ticks, such as the common dog tick, have a hard shield behind their mouthparts and are shaped like a flat seed when unfed. Soft ticks, on the other hand, do not have a hard shield and are shaped like a large raisin.

– Tick Behavior: Ticks do not jump or fly, contrary to popular belief. They find their hosts by detecting their breath, body odors, body heat, moisture, or vibrations. Many tick species, particularly Ixodidae, lie in wait in a position known as “questing,” where they cling to leaves and grasses by their third and fourth pairs of legs, waiting for a suitable host to pass by.

– Tick-Borne Diseases: Ticks are known to transmit various diseases to animals and humans. Some of the diseases that can be transmitted through tick bites include Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, and tularemia. The risk of tick bites and tick-borne diseases is highest in early spring through late fall.

– Preventing Tick Bites: To protect yourself and your family from tick bites, you should:
– Wear protective clothing, such as long-sleeved shirts, long trousers, boots or sturdy shoes, and a head covering. Ticks are easier to detect on light-colored clothing.
– Tuck trouser cuffs into socks and tape the area where pants and socks meet to prevent ticks from crawling under clothing.
– Use insect repellents that are effective against ticks, following the product instructions.
– Check your body and your child’s thoroughly for ticks after spending time in tick habitats, such as tall grass, leaf litter, or shrubs.


Wasps are a diverse group of insects in the order Hymenoptera, suborder Apocrita. They are neither bees nor ants and can be further divided into two primary subgroups: social and solitary. Here are some key points about wasps:

– Types of Wasps: There are various types of wasps, including social wasps, such as yellow jackets and hornets, and solitary wasps. Social wasps live in colonies and have a caste system consisting of queens, drones (males), and workers. Solitary wasps, on the other hand, live alone and do not form colonies.

– Physical Characteristics: Wasps are distinguishable from bees by their pointed lower abdomens and narrow “waist,” called a petiole, that separates the abdomen from the thorax. They come in a range of colors, from yellow to brown, metallic blue, and bright red, with the brighter colored species often belonging to the Vespidae family.

– Ecological Significance: While wasps are often associated with their ability to sting and disrupt picnics, they play a crucial role in maintaining the balance of ecosystems. Social wasps, such as those in the UK, can capture millions of kilograms of insect prey each summer, helping to control pest populations. Solitary wasps also contribute to natural pest control by feeding on other insects and spiders.

– Interactions with Humans: Wasps may sting humans if they perceive us as a threat, although they do not lose their stingers like honey bees do. It is important to appreciate the ecological benefits of wasps while ensuring a safe environment for both plants and humans.

Deer Flies

Deer flies, also known as Chrysopsinae, are bloodsucking insects that are considered pests to humans and cattle. Here are some key points about deer flies:

– Physical Characteristics: Deer flies are large flies with brightly colored compound eyes and large clear wings with dark bands. They are larger than common houseflies and smaller than horse flies. The typical size of a deer fly ranges from 0.25 to 1.25 inches long. They have distinctive purple or green bands on their blue or yellow-green wings, and their mouths extend downward and jut out ahead of the rest of the head.

– Biting and Feeding: Female deer flies feed on the blood of various mammals, including humans, pets, livestock, and deer. They have two pairs of mouthpart “blades” that they use to cut the skin, and once the skin is injured, they lap up and ingest the exposed blood. These flies usually target high areas on a host’s body, such as the head or neck. In contrast, horse flies feed on various areas but often prefer the legs.

– Habitat and Activity: Deer flies are plentiful in damp, wooded, or wetland environments, such as marshes, ponds, and streams. Their activity peaks in June and July throughout much of their distribution area. During the early stages of their life cycle, the larvae require an aquatic environment, and they pupate and eat tiny insects found around muddy edges of the water.

– Diseases and Allergic Reactions: Deer flies can transmit various parasites and diseases, including tularemia, anthrax, anaplasmosis, equine infectious anemia, hog cholera, and filiariasis. The saliva of the fly contains anti-coagulants, which can cause severe allergic reactions in some individuals. However, their role in disease transmission is minor compared to ticks and contact with infected small game animals.

– Control and Prevention: Deer flies are difficult to control because insecticides cannot be applied in the sensitive wetlands where their larvae typically develop. Some methods, such as the use of traps or manipulating the habitat by removing unnecessary woody plants or draining wet areas, may be moderately helpful in reducing their populations. When outdoors, using repellents such as DEET and wearing clothing to cover exposed body parts can provide some protection against deer fly bites.

Horse Flies

Horse flies, also known as Tabanidae, are large, aggressive flies that can inflict painful bites on animals and humans. Here are some key points about horse flies:

– Physical Characteristics: Horse flies have a gray or blackish body and are 10 to 30 millimeters long. They usually have wings lacking dark areas, but some species have entirely dark wings. They have large eyes that are usually green or purple with horizontal stripes. Horse flies have six legs and are stout-bodied and without bristles, and they all have short antennae.

– Biting and Feeding: Only female horse flies bite land vertebrates, including humans, to obtain blood. They are attracted to movement, shiny surfaces, carbon dioxide, and warmth. Once on a host, they use their knife-like mouthparts to slice the skin and feed on the blood pool that is created. Bites can be very painful, and there may be an allergic reaction to the saliva.

– Habitat and Activity: Horse flies are commonly found in both suburban and rural areas near bodies of water, which serve as breeding sites, and where mammal hosts are most abundant. They are most evident on windless, hot, sunny days. Horse flies often rest on paths and roads, especially in wooded areas, where they wait for potential hosts.

– Diseases and Allergic Reactions: Female horse flies can transfer blood-borne diseases from one animal to another through their feeding habit. In areas where diseases occur, they have been known to carry equine infectious anemia virus, some trypanosomes, the filarial worm Loa loa, anthrax among cattle and sheep, and tularemia. They can reduce growth rates in cattle and lower the milk output of cows if suitable shelters are not provided.

Biting Midges

Biting midges, also known as no-see-ums or punkies, are tiny flies that can be severe biting pests of humans, pets, livestock, and wildlife. Here are some key points about biting midges:

– Physical Characteristics: Biting midges are small, ranging in size from 1-3 millimeters in length. They typically have a grayish or reddish color, with some species appearing more reddish when filled with blood. The wings of many species, including those that feed on humans, contain dark patterns, giving them a grayish appearance.

– Habitat and Breeding: Biting midges commonly breed around the edges of water bodies, such as damp soil, marshes, and intertidal sand. The complete life cycle, from egg to larva to pupa and finally to the adult stage, can occur in two to six weeks, depending on the species and environmental conditions.

– Biting Habits: Only the female biting midges feed on blood, using it as a protein source to develop their eggs. They are most active during calm conditions, biting around dawn, dusk, and even throughout the night on overcast days. Biting midges can be a nuisance to humans, and their bites are often irritating, painful, and can cause long-lasting painful lesions for some people.

– Control and Prevention: Biting midges can be managed by using insecticides, trapping them with carbon dioxide, and repelling them with DEET, oil of Eucalyptus, or Icaridin. Their larvae have also been shown to be susceptible to treatment with commercially available preparations of Bacillus thuringiensis israelensis.


1. What is the most dangerous insect in Canada?

The most dangerous insect in Canada is the mosquito, which can transmit diseases like West Nile virus and malaria to its victims. Mosquitoes are responsible for killing approximately one million people worldwide each year.

2. Are there any venomous spiders in Canada?

Yes, there are venomous spiders in Canada, including the black widow spider, brown recluse spider, and hobo spider. While these spiders can deliver painful bites, they are not typically aggressive and will only bite in self-defense.

3. Do all ticks in Canada carry Lyme disease?

Not all ticks in Canada carry Lyme disease. The variety known as deer ticks is the primary carrier of Lyme disease, and they are most prevalent in the northeastern and upper midwestern states of the United States. However, there have been cases of Lyme disease in most states in the U.S., as well as in Europe and Asia.

4. What are the dangers of deer fly bites?

Deer fly bites can be painful and irritating, and in some cases, they can transmit diseases such as tularemia, anthrax, and anaplasmosis. These flies are most active in June and July and are often found in damp, wooded, or wetland environments.

5. How can I protect myself from dangerous insects in Canada?

To protect yourself from dangerous insects in Canada, you can take the following precautions:

– Use insect repellent containing DEET, oil of Eucalyptus, or Icaridin when spending time outdoors.
– Wear long sleeves, pants, and socks to minimize exposed skin.
– Avoid areas where insects are known to breed, such as still pools or ponds, during hot weather.
– Remove standing water from your property to eliminate mosquito breeding sites.

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