Wasps & Hornets
Wasps and hornets are structure infesting. They forge among fruit, gardens, farms, scavenge garbage and prey upon other insects. They would not be such a nuisance or threat to humans if not for their habit of nesting in and on structures. It usually becomes more apparent later in the summer, when populations have grown and can become agitated from disturbances and become more protective of nesting. Wasps and hornets have barbless stingers which enable them to sting repeatedly.
Umbrella Wasp
Umbrella wasps are brown with thin yellow markings and about 15mm in length. The native paper wasp is much more docile than other paper wasps. They build introverted, exposed cell umbrella like nests, under eaves and on structures. The number of wasps living upon the nest is small, usually less than a dozen and they rarely sting unless the nest is disturbed. These wasps feed on insect larvae and rotten fruit. The nest itself is a single layer of cells with no covering and is suspended from a stock.
A newer species, the European paper wasp is now found in Ontario and it is more aggressive than the native species. It prefers cavities for its nest and will build on a vertical surface as well. The native paper wasps usually begin a new nest each year, which will result in a smaller colony but the European paper wasp often stay in the nest all winter, and will use it again resulting in larger colonies.
Yellow Jacket
Yellow Jackets Wasps are black and yellow, measuring 12- 18 mm. They forage over long distances, making it difficult to locate their nests. There are four common species of yellow jackets in Ontario.
The fertilized queen can usually be found overwintering inside buildings, or wood piles. In spring a new colony is established by the queen. This can be in a hollow stump, below ground in a cavity, in a wood pile, a hollow tree, or other protected voids such as attics. The actual nest has many layers combs that are surrounded by paper, which is made from wood fibres.
Some species may also suspend from eaves, roof, rafters, and tree branches. The old nest will not be reused by these wasps.
Mud Dauber
Mud dauber wasps are solitary wasps with very long legs. The adults are a metallic blue or black with yellow. They measure 30-35 mm. These wasps construct mud nests which they attach to ceilings or walls. They lay their eggs in the mud hallows with small insects or spiders that were captured and sealed in. The larvae then have food waiting for them upon hatching. The mud dauber rarely are bothersome or sting.
European Hornet
The European Hornet worker is brown and black with amber coloured wings. These hornets measure 18-30 mm in length. The European Hornet is the only true hornet in Ontario. It is very active at night and is a strong flyer. The nest is similar to that of the Bald-Faced Hornet other the its nest is a brown colouring rather than the gray/blue. The nest is often built in the wall voids of buildings.
Bald-Faced Hornet
Bald Faced Hornets are black and white and measure 12-18 mm. The Bald-Faced Hornet builds a large gray/blue soccer ball sized paper nest, with a single entrance off centre at the tip. The combs are horizontal with a multi layered cover surrounding and protecting them. Usually a nest is suspended among the branches of a tree or attached to a structure but can also be built underground. These wasps can become aggressive if the nest is disturbed, but will tolerate human approach. Bald-Faced Hornets are not true hornets but a type of paper wasp. As a result of their size, colouration and habits they are commonly classified incorrect.