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Brampton, Ontario

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Wasps & Cluster Flies



wasp nestWhile there are many varieties of wasps across the GTA and Ontario, the two that pose the greatest threat to homeowners and businesses are yellow jackets and hornets. Their painful stings can be a serious health threat to humans and animals, especially if a person is allergic to wasp venom.

Wasps are excellent papermakers and build their nests in a variety of places, often choosing sunny spots. Each spring, the queen gathers wood fibre and chews it into a papery pulp, out of which she starts to build the nest for brooding purposes. All wasps have the ability to chew, but only the female possesses a stinger.

Yellow jackets, the most commonly encountered wasp in Ontario, are easily identifiable by their yellow-striped abdomen, lack of body hair, and thinner, elongated bodies. Yellow jackets make enclosed nests and can be found in the ground; beneath logs; in trees, eaves, and attics; under siding; and in gaps in brick or in building walls.

The queen lays all the eggs; though most eggs develop into sterile workers. A queen will lay an average of 100 eggs per day, which hatch and develop throughout the summer. Yellow jacket nests generally last for only one season before dying off in late autumn, usually after the second hard frost.   That said, newly hatched queens survive the winter hiding under loose bark or in crevices, and lay eggs in the spring to start a new colony.

Similar to yellow jackets, hornets are smooth-looking, with black bodies and yellow marks on their head and abdomen.   Equally as aggressive as yellow jackets, hornets will protect their territory. Unlike bees, wasps can sting people multiple times.

Hornets are social insects. They live in colonies that may contain between 100-400 members at their peak. Hornets are famous for their large, grey-coloured, enclosed paper nests, often tucked under eaves of decking that is more than three feet off the ground. The nests are also very distinct looking, shaped like footballs or inverted teardrops.

Wasps become a real problem in late summer, when their nests are bigger and they need to supply large amounts of food for the colony. They will also aggressively defend their nests. Adult yellow jackets are very fond of pop and other sugary foods; this is why they invade garbage cans, decks, patios, and picnics.

For more information about how  City & Country Pest Control  can assist you with wasp infestations, contact us at 905-455-1102  or

Cluster Flies

cluster fly headFew pests are as annoying as the cluster fly. While people are accustomed to swatting flies in the warm summer months, cluster flies don’t make an appearance until the autumn. They then search for sunny, warm spots to hibernate over the cold winter months.

Cluster flies get their name because they enter a home or building in the fall and gather together in clusters, usually in the attic or upper regions of buildings, before and during hibernation.

Cluster flies look like common houseflies, but are larger and much slower. They are dark grey in appearance, with checkered black and silvery-black abdomens. Their wings overlap over the abdomen when at rest. The annoyance of cluster flies usually begins mid-August and may continue until April of the next year.

They are attracted to light, becoming active in early spring or on warm, sunny days in the winter, banging into lights and windows in a confused attempt to go back outside. They often drop to the floor on their backs and spin noisily about until exhausted. Aside from being a buzzing nuisance, a large number of dead cluster flies can provide a steady diet for mice and other pests.

Unlike other flies, cluster flies do not breed, lay eggs, or feed indoors. Adult cluster flies leave their protected overwintering sites in the spring and lay eggs in the soil, where the hatching larvae become parasites in earthworms; they then pupate and emerge as adults, ready to be a nuisance.

The cluster fly gestation period can last three to five weeks. They can also produce more than four generations of cluster flies per season.

During the onset of autumn, adult cluster flies look for protected sites where they can spend the winter, including:

  • and attics
  • Under the bark of dead and dying trees
  • Crevices and voids in sheds, garages, barns, and houses
  • Between walls and other man-made structures.

In the spring they awaken, ready to start the cycle anew.

For information about how  City & Country Pest Control  can deal with cluster flies for you, contact us at 905-455-1102  or


  1. “Yellowjacket Wasps – Late Summer Pest,”  University of Tennessee;, last accessed April 5, 2013.
  2. “Cluster Flies,”  Pennsylvania State University, 2013;, last accessed April 8, 2013.

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