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Wasp Facts, Identification, & Control

Common Wasps Associated with Structures in Canada

Wasps belong to the insect order Hymenoptera, which is a general term for wasp-like insects and also includes ants and bees. More than 500 species of wasps inhabit Canada, of which a good number, are social creatures that live in colonies ranging from half a dozen to 15,000 members. The females have egg-laying structures called ovipositors, which also work as stingers and can inflict painful stings when provoked. The most common pest wasps associated with structures in Canada are hornets, yellow jackets, paper wasps, and mud daubers. The wasps are usually sighted during summer and early autumn. Depending on the species, wasps construct mud nests, papery nests from masticated plant matter, or nest in ground. When faced with wasp problems, homeowners should always consult pest control professionals, as pest wasps are often territorial, can be aggressive, and become very dangerous in large numbers.


What does a Wasp look like?

A typical wasp is hairless, unlike common species of bees. Wasps possess three distinct body parts: head, thorax, and abdomen. The thorax is joined to the abdomen by a constricted petiole giving the appearance of a thin/slender waist. The thorax has three pairs of legs and two pairs of membranous wings which are used for flying. Like most insects, the head bears mouth parts, sensory organs, compound eyes, and segmented antennae. The last segment of the abdomen in female wasps is modified into the egg-laying ovipositors. The body size and colour of a wasp varies depending on species. Yellow jackets and hornets are stout and very colourful with bold yellow, white, and black markings on their bodies and faces. Paper wasps on the other hand are relatively long and thin-bodied (16 – 25 mm), long-legged, and have yellow-reddish and black markings. Mud daubers are very distinct, with very long bodies, 13 – 25mm long, with either long or stalked abdomen. Compared to other wasps, mud daubers are not so colourful; they are mainly black with occasional pale-yellow markings.

Image of chalcidid wasp
Chalcidid wasp fragments pictured for identification[/i]


What does a wasp nest look like and where do you find them?

Wasp nests vary in shape, size and location depending on the species. Paper Wasps: Nests are constructed of paper-like material obtained by chewing and gluing plant material together. The nests are single layered, comb-like with no definable enclosure and consisting of 150 to 300 cells. The nests are stalked, attached to an object by a long stalks or stems called pedicel. Typical places where paper wasps attach their nests include fences, tree branches, twigs of trees and shrubs, eaves, door and window frames, exterior joists and soffits. Yellow Jackets and Hornets: Nests are also constructed of plant materials; however, they are multi-layered and consisting of five to nine combs with a total of 1,500 to 3,500 cells. The nests can either be exposed or protected in a paper envelope. Some yellow jack nests are the size of a soccer ball. Nests are typically found in hollow trees, wall voids, inside structures such as sheds, garages, and attics, and in trees and brushes. Some hornets and yellow jackets nest in ground. Ground nests are located typically in areas clear of vegetation. Mud daubers are solitary wasps. As the name suggests, mud daubers construct nests out of mud. A typical mud dauber nest is about 20-25 mm long. Such nests are generally plastered side by side forming a cluster of up to 100 to 120mm wide. Mud daubers like to build nests in sheltered sites, such as protected building structure and walls.


What do wasps feed on?

Most wasps primarily feed on nectar, fruit juices, or honey dew from plants. However, the most common wasp pests we encounter are primarily scavengers or carnivores that prey on other insects. Wasps are beneficial because of their predatory behaviour, which helps control insect pests in agricultural crops and gardens. The scavenger behaviour also draws wasps to human environments or activities where food is present, which makes the insects nuisance pests.

Life Cycle / Reproduction

Wasps undergo complete metamorphosis before becoming adults. The full process takes approximately six weeks. After eggs hatch, the new larvae feed on insects brought in by stinging female workers for a few weeks. Larvae then enter the pupal stage, a cocoon-like period where immatures transform into adult wasps over several more weeks. The queen typically only produces workers at the beginning of the season, and the workers care for the young as the queen continues to lay eggs.

Wasp colonies reach peak numbers during the late summer and early fall. A reproductive generation of males and females is produced around that time of year. Males die shortly after mating, with the rest of the colony dying off as temperatures drop. Fertilized females, or queens, overwinter and lay eggs in the spring to begin new colonies. Female wasps often hibernate in areas of the house with less traffic such as attics, barns, garages, or other accessible storage spaces.

Wasps as Pests: Should You Be Concerned?

Homeowners should remain highly concerned in regards to possible wasp infestations. Aside from cosmetic damage, common wasps do not cause structural damage to houses or buildings. However, the insects may cause annoyance as they interfere with outdoor and backyard recreational or social activities such as swimming, picnics, BBQs, and gardening. Wasps are typically attracted by food, beverages, and garbage associated with such social events. Most wasps are not aggressive and will not sting unless protecting their nests or provoked. If provoked, they will sting and unlike bees, they are capable for stinging multiple times. Stings from wasps can be a health concern because they may cause severe allergic reactions which can result in anaphylactic shock and death.

Prevention: What Can You Do to Prevent Wasp Colonies in Your Home and on Your Property?

Wasp-proofing: Queens overwinter in protected shelters in homes and emerge the following spring to start new colonies. The new colonies generally begin in close proximity to where the queens overwinter. Homeowners should wasp-proof homes and property by inspecting, identifying, and sealing or excluding all potential entry points and protected sites, such as cracks in windows and doors, poorly sealed holes for ventilation lines, spaces in soffits, recessed lighting fixtures, or gaps leading to voids in walls or baseboards. Any opening a quarter of an inch or larger represents a potential entry point. Wasp-proofing prevents or reduces the chances of queens entering structures to overwinter and establish colonies the next season.

Habitat Modification: Denying wasps food generally leads to the insects moving on. Reducing or eliminating factors that attract and encourage other insects such as flies, ants, and spiders, which in turn provide food for the wasps, also eliminates potential infestations. Wasps like to nest in protected areas, so trimming back bushes, twigs, shrubs, and trees eliminates potential nesting sites. Remove old, non-active wasp nests from previous seasons to prevent infestation relapses.

Human Behaviour Modification: Homeowners should adopt practices which do not attract wasps. During outdoor activities such as picnics or parties, homeowners should keep all food sealed in airtight containers, clean-up spills promptly, and cover trash with tight-fitting covers. Store garbage bins no less than 50 feet away from vulnerable entry sites or outdoor activities. During summer months, outdoor garbage bins should be placed away from entranceways and should be emptied on a daily basis.

It is important not endeavour to eliminate nests without proper guidance and knowledge. Call a professional pest control expert if you’re experiencing a wasp infestation in or around your home or business.

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