What are Wasps?

Wasps (order Hymenoptera), by name alone, can instantly invoke fear of being swarmed and stung. In fact, often an encounter with a lone flying, buzzing, black and yellow insect can cause panic.

What many do not know is that most of the 30,000 identified wasps worldwide are solitary and do not sting. They are also beneficial to helping to control pests that humans find a nuisance in their homes or business or that negatively impact the agriculture industry (by damaging crops).

Wasps are categorized into 2 groups - social and solitary. Of the 30,000 species, about 1,000 (just 3%) are social wasps. Social wasp colonies are started from scratch each spring by a queen who was fertilized the previous year and survived the winter by hibernating in a warm place. These wasps have a worker caste system and rely on the queen to build the population. These wasps are mostly aggressive and will swarm and sting to defend their nest. Solitary wasps do not form colonies and tend to be far less aggressive. These wasps often use their stinger to hunt and paralyze their prey with their venom.

Here in Canada, we have 500+ species, most of which are social, and live in colonies with thousands of members. Wasps are often observed more in summer and early fall, which is when their colonies are large, and they are out seeking food.

The most common nuisance wasps in Ontario are yellow jackets, paper wasps, mud daubers and bald-faced hornets. Many use “wasp” and “hornet” interchangeably, and at times confuse wasps and hornets. Hornets are wasps, and they share many similarities to Yellow Jackets. There is only one true hornet specie, and it is not the bald-faced hornet. This species is far closer to a yellow jacket wasp than a true hornet.


What do Wasps look like?

Wasps have a head, thorax and abdomen. A narrow petiole connects their thorax and abdomen and gives the appearance of a narrow waist. Most wasps are hairless, have 6 legs and 2 pairs of wings. They are smaller than hornets, averaging 1 inch or less in size, however some species can grow up to 1.5 inches long.

They also come in a wide variety of colours, from yellow to brown to metallic blue and even bright red. Yellow jackets are bulky with vibrant yellow, black and white markings, while paper wasps are long and thin, with long legs, and yellow-reddish and black markings. Mud dauber wasps also have long bodies, but most types are dull in colour, with black with faint yellow markings.

               Wasp in nature     A dead wasp


What do Wasps Eat?

Most wasps eat honeydew secretion from plants, nectar or fruit juices. Some species also prey on insects, especially spiders and flies.

Wasps are also attracted to human food, especially high fructose corn syrup-based treats (which contain glucose, sucralose or sucrose) and exposed/decomposing meats.


Wasp Nests

All wasps construct nests, which can vary in location, size and shape based on the species. In comparison to bees, who secrete a wax-like substance to build their nest, most wasps create a papery material by chewing wood fibers into a pulp. Mud dauber wasps, as per their name, make these nests from mud.

                        wasps building their nest

Nests, for example, can be aerial or ground, can resemble paper-like balls the size of soccer balls or basketballs with multi-layers (yellow jackets and bald-faced hornet), fist-sized mud nests (mud daubers), or be single layer comb-like nests with no paper enclosure (paper wasps). 

Wasps typically build their nests within or handing from:

  • Trees, shrubs or bushes
  • Fences, soffits, exterior joists, door or window frames
  • Porches or decks
  • Sheds, garages and barns
  • Hollow trees
  • Underground burrowers
  • Sandy or bare soils (away from vegetation)
  • Wall voids, attics, basements or crawl spaces
  • Abandoned vehicles
  • Some species will re-use abandoned nests from other wasps or bees or small mammals.

An aerial wasp nest in a tree


If you come across a nest whose location does not pose a threat to your home or business, leave it be. Also do not approach a nest that appears to be active. Active nests often have wasps swarming the exterior of them. The wasps are social, and feel threatened, they may swarm and sting in defense. Some wasps, like the bald-faced hornet, are very aggressive, and will even chase you for long distances in attempts to sting you.


The Lifecycle of a Wasp

In early spring, fertilized females (from the previous generation) emerge from overwintering, to become new queens. She will find a suitable place for a new nest and start to build it. She will lay her fertilized eggs in the individual cells within the nest which will develop into the first-generation non-fertile female worker wasps. They will take on the duties of expanding the nest, seeking food and caring for the queen and her young. The queen will remain in the nest and concentrate on egg laying to continue to build up the colony members.

In late summer to early fall, the queen will lay eggs which will develop into adult male and fertile females. These wasps will leave the nest to mate, where shortly after the males will die. The newly fertilized female wasps will be the new queens in the following spring. They permanently leave the colony to find their own protective shelter to overwinter. The rest of the colony will die in winter, leaving these overwintering future queens as the only survivors.


Do Wasps Sting or Bite?

Social wasps will sting, and will sting multiple times if provoked or threatened. This is because these types of wasps are often territorial, very aggressive, and a danger in large numbers.

Social wasps emit a pheromone when under distress attracts any nearby colony members, and sparks a swarming, stinging attack. Non-social wasps, like the mud dauber, can sting is touched, but typically do not swarm as they are not aggressive nor do they defend their nest.

Wasp stings are painful and can cause swelling and redness around the sting site, as well as severe allergic reactions or even death. If you have any concerns after being stung by a wasp, seek professional medical assistance.


Damage Caused by Wasps

Wasps cause superficial damage to a home or building, and they are an eyesore. They are mostly obnoxious, uninvited guests to outdoor activities or events. They are bothersome at BBQs, picnics, outdoor parties, during gardening, and even during a simple meal on a back deck or patio.

Wasps are a serious concern for people and pets because social wasp species will sting, and can cause severe allergic reactions.

Despite the above, wasps do play an important role in our ecosystem. They are effective at helping to control common nuisance insect populations (like flies and spiders), that we do not want in our homes or businesses. They are also beneficial in helping to control crop damaging pests’ populations.


How Does a Wasp Infestation Happen?

In general, queens will overwinter in warm protected locations to survive the winter so that they can awaken in the spring to start the next generation of wasps. In seeking shelter, in late summer and early fall, they enter homes or structures through crack and crevices. In the spring, when they become active, they often construct their new nests close to their overwintering location. As summer passes, the nests grow, as does the population of wasps.


Signs of a Wasp Infestation

Obvious signs of a wasp infestation are the presence of an active nest and wasps swarming around.


How to Get Rid of Wasps

As new nests are typically built in locations close to where the queens overwintered, wasp-proofing your home and business helps to reduce the chances of fertilized female wasps gaining access, and therefore decreases the chances of an infestation the following year.

We advise against DIY wasp pest control, especially when colonies are large. Social wasps will fiercely protect their nest if threatened or provoked, and they can sting repeatedly.

Here are some helpful tips to prevent a wasp infestation:

  • Inspect your home or building’s exterior to identify cracks, crevices or openings for wasps, and other insects, which provide a food supply for wasps. Check:
    • Windows, doors, siding, eaves and fascia boards.
    • Roof joints and behind chimneys.
    • Places where utility pipes, plumbing, wires or cables enter the building.
  • Seal all exterior cracks, crevices, gaps and holes with quality silicone or silicone-latex caulk.
  • Repair or replace torn window and door screens or weather stripping.
  • Install or repair screens in roof and soffit vents.
  • Trim back trees, shrubs and bushes.
  • Remove any non-active wasp or hornet nests from previous seasons.
  • Store garbage, green bins and recycling with tight-fitting covers away from your home or business.
  • Regularly clean garbage cans, green bins and recycling receptacles to remove sugars and proteins, will can attract wasps.
  • In the summer, help keep wasps away (especially yellow jackets) from outdoor entertaining areas by keeping food sealed or covered, and cleaning up spills promptly.
    • Some have found relief from nuisance yellow jackets but placing a cup fruit juice or pop away from outdoor eating areas, which draws them away.

If you have a wasp infestation in your home or business, or concerns about an active wasp nest, contact a licensed pest control professional to help you safely get rid of wasps.

Infested with hornets?  Learn more about how to get rid of hornets

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