Bald-Faced Hornets

Identification

  • Colour Black and white
  • Size 13 to 20 mm in length
  • Also known as Dolichovespula maculata
  • Notes The bald-faced hornet, or Dolichovespula maculata, gets its name from its strikingly white face. Calling the insect a hornet, however, is technically incorrect, as true hornets are distinguished by their large size, potent sting, aggressive behaviour, and aerial nests. While the bald-faced hornet is large in size and nests above ground, the pest is actually a yellow jacket.

How to identify Bald-Faced Hornets

Unlike many other species of wasps and yellow jackets, which are black and yellow in colour, the bald-faced hornet is uniquely black and white. The stinging arthropods feature coloured patterns and markings on the abdomen that serve as a primary source of identification between different species while also identifying the role each individual plays within the colony. Typically, the insects range from 13 to 20 mm in length, with workers remaining relatively small in size and queens ranking as the largest members of bald-faced hornet colonies.

Signs of an infestation

Bald-faced hornet nests are grey and papery, approximately 60 cm tall, 45 cm across, and shaped like a football. Spotting such an object hanging from trees, bushes, or the eaves of buildings indicates a bald-faced hornet infestation. Additionally, people in infested areas may notice the insects coming and going from their nests during the warmer months.

Bald-Faced Hornets Removal

Bald-faced hornets aggressively protect their nest, making treatments by a pest control professional the only guaranteed way to eliminate the colony. Therefore, inexperienced or untrained individuals should not attempt to control or remove a nest without professional help. Calling a local pest control service for treatment and removal of the nest is the best and safest solution for bald-faced hornet management.

How to prevent Bald-Faced Hornets from invading

Save for removing all foliage from the yard, total prevention of bald-faced hornets is impossible to achieve. However, limiting access to overwintering sites indoors can be accomplished by finding and sealing all cracks in the foundation of the home or building. Replacing broken or torn window and door screens also deters the pests from entering. Additionally, tightly seal all outdoor trash receptacles, and trim shrubbery and trees so they offer as few nesting sites as possible.

Habitat, Diet, and Life Cycle

Habitat

Bald-faced hornets live exclusively in North America. Except for desert environments, the pests are distributed throughout the contiguous United States, Alaska, and Canada. Queens build nests anywhere from about one to 18 metres off the ground. Common nesting sites include bushes and shrubberies, trees, and the eaves of buildings.

Diet

Adults primarily feed on nectar, pollen, and other sweet liquids, while larvae are fed meat, animal carrion, and soft-bodied insects like caterpillars, aphids, and the workers of other yellow jacket and hornet species. As foraging insects, bald-faced hornets frequently disturb picnics and trash bins for sugary beverages and chunks of prepared meat.

Life Cycle

In early spring, traditionally between April and June, inseminated female bald-faced hornets emerge from under loose bark, the interior of hollow logs, and similar types of overwintering sites. After mating in the fall, the female will find a suitable location, build the beginnings of a nest, and deposit the first bunch of eggs inside. Once the first brood matures into sterile female workers, the initial female becomes the queen and delegates all of her responsibilities, save for reproduction, to the workers.

Bald-faced hornet colonies continue to grow throughout the summer months. The average nest size fluctuates between 200 and 400 workers but can swell to as many as 700 to 1,000 individuals. From July to September, fertile females and males are produced for mating purposes. Right before the first freeze, all members of the colony die except for the newly fertilized queens. The cycle repeats once a year.

Commonly Asked Questions

How worried should I be about Bald-Faced Hornets?

Though certainly a nuisance pest, the bald-faced hornet neither causes structural damage to buildings nor transfers diseases to humans. Still, given the way they aggressively protect their nests, bald-faced hornets are dangerous. Stings generally only cause some pain, swelling, and redness; however, people who suffer from an allergic reaction may be at risk of experiencing anaphylactic shock if stung.

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