Identify Your Pest Flying insects Bald-faced hornet
Bald-faced hornet
Dolichovespula maculata · Also called: White-faced hornet, bald-faced aerial yellowjacket
The bald-faced hornet is a large black and white wasp that builds a grey, football-shaped paper nest in trees, shrubs or under eaves. Nests grow fast through summer and are often noticed late in the season, when falling leaves bring them into view.
Size About 13 to 20 mm long; queens are largest
Colour Black with ivory white markings on the face and tail end
Key feature Black and white body with a white face and no yellow anywhere
Season May to the first hard frost; nests largest in August and September
Where Tree branches, shrubs, eaves, sheds and corners of fences or decks
What it looks like
The bald-faced hornet is larger and bulkier than a yellowjacket. Its body is black with creamy white marks on the face, at the front of the thorax and at the tip of the abdomen. There is no yellow on it, which quickly sets it apart from most yellowjackets. Despite its name, it is not a true hornet. It is actually a kind of yellowjacket.
Its nest is just as distinctive. It is a closed grey paper ball or teardrop, often the size of a football by late summer, with swirled bands on the outside and one entrance hole near the bottom. Nests usually hang in plain sight a metre or more above the ground, though leaves can hide them until fall.
Often confused with
Yellowjacket
Aerial yellowjacket
Blackjacket
Signs to look for
Grey paper ball in a tree
Black and white wasps
Hornets on weathered wood
Nest found after leaves drop
Risks and damage
Bald-faced hornets defend their nest fiercely. Walking past, mowing nearby or bumping a branch can bring out many hornets at once, and each can sting more than once. Stings are painful and swell, and people with a venom allergy may need urgent medical care. Away from the nest they are mostly harmless. They hunt flies and other insects and rarely bother picnic food. Their nests do not damage buildings.
In Alberta
Bald-faced hornets are found across Alberta, from Calgary and Red Deer to Edmonton and the northern forests. Queens start nests in late spring, and nests peak in August and September. Hard frosts end the colony, so many nests are only spotted in fall, after leaves drop and the hornets have died.
Bald-faced hornets make their own paper. They chew wood fibre with saliva and spread it in thin strips, and wood from different sources creates the swirled grey bands on the outside of the nest.
How to keep them out
Scan trees and eaves early
Trim shrubs near the house
Look before you mow or prune
Close gaps in outbuildings
When it is time to bring in a professional
Get professional help if a nest is near a door, window, walkway or play area, or sits where a mower, ladder or hedge trimmer could disturb it. Nests high in trees or inside sheds are hard to reach safely. Technica’s licensed technicians can handle active nests with the right protective gear.
Frequently asked questions
Is a bald-faced hornet a real hornet?
No. Despite the name, it is a kind of yellowjacket. True hornets belong to a different group, and none are established in Alberta.
Can I leave a nest that is far from the house?
Often, yes. A nest high in a tree at the back of a large yard may cause no trouble, and the hornets eat many flies and other insects. The colony dies with hard frosts and the nest is not reused. Keep people and pets away from it until then.
What should I do with an empty nest in winter?
After several hard frosts the nest is usually empty, and new queens do not return to it. Many people leave it to fall apart or take it down with gloves on. If you are not sure it is empty, leave it until after a few more hard frosts.