Bald-faced Hornets. How to Spot, Avoid and Remove a Nest

Adults are about 7/8 inch long, black, with white to cream markings on the front of the head and at the tip of the abdomen.¹ That black and white look is the quickest tell, since yellowjackets are yellow.

Despite the name, it is not a true hornet. It belongs to the yellowjacket genera.^2,4 The only true hornet in Ohio is the European hornet, which is 1 to 1 1/2 inches long with a reddish brown thorax and a yellow face.⁴

The nest gives it away. It has three or four tiers of combs inside a thick, layered outer shell with one opening at the bottom.¹ It is built of weathered wood chewed to fiber and mixed with saliva.³ See the main guide and the yellowjacket guide for the other look-alikes.

The queen spends the winter under bark or in a hollow tree, then comes out in spring to start a nest.³ Iowa State puts nest starts in April or May.¹

An early nest is no more than about 1.5 inches long.³ Offspring take 20 to 25 days to develop in the Midwest, so each generation is bigger than the last.³ By the end of summer the colony peaks at 100 to 400 workers.¹

In fall the colony makes males and new queens. The fertilized queens hibernate and the rest of the colony dies.¹ Nests are used one season only.³ The old nest is not reused, so you do not need to hunt for the same one next year.

• A large gray paper nest hanging from a tree branch, often in wooded areas.¹
• The same nest on a shrub, a utility pole or house siding.^1,3
• Black and white wasps going in and out of one opening at the bottom.¹
• Hornets that dive at you when you get close, usually within 3 feet.¹
• A nest that seems to show up overnight in August. Nests start tiny and are often hidden by leaves, so most go unnoticed until mid to late August.³

Look up before you trim a hedge or hang a feeder.

Bald-faced hornets are not especially aggressive, but they sting if the nest is disturbed or one is threatened.¹ They usually attack anyone who comes within 3 feet of the nest.¹ They can sting more than once.²

UC IPM warns that many yellowjacket stings at once can damage the kidneys.⁵ One to two people in 1,000 are allergic to bee and wasp stings.¹⁰

An Ohio State BYGL writer rates a single sting from these wasps as no more than a 2 on the 1 to 4 Schmidt pain scale. Most painful run-ins come from poorly planned attempts to remove a nest.²

For care, Ohio State says use an ice pack in 10 minute rounds, take an antihistamine, and get medical help for more than 10 stings or any sting in the mouth or around the eyes.⁷

First ask if you need to act. Iowa State says nests along walks or near doors justify control, and nests away from people should be left alone.¹ Ohio State says each nest dies out by winter anyway.²

If you do it yourself, Iowa State describes an aerosol made for hornets that sprays a thin stream up to 20 feet. Treat at night, when most hornets are in the nest. Wear a thick jacket, long pants tucked in, gloves and a hat. Spray the entrance first, then wet the whole nest.¹

Do not take the nest down until all the hornets are dead. That can take a day or two because foragers may have been away.¹

Ohio State advises having a professional remove any nest that threatens people.⁷ That is the right call for a high tree nest or a nest in a wall. Ask the company if it treats at night and what a return visit costs. Commercial traps are usually not attractive to bald-faced hornets.²

One national guide averages $625 to remove bald-faced hornets. Other wasps are cheaper, with paper wasps at $385 and hornets at $450.⁶ The most common wasp job runs $212 to $875.⁶

Where the nest sits matters. Attic nests run $325 to $450 and wall nests $350 to $875.⁶ Tree canopy nests have no separate price in that guide, only the $625 bald-faced average.⁶

Method matters too. Aerosol averages $125, dusting $200 and vacuuming $250.⁶ A do-it-yourself kit with spray, dust and a bee suit costs $57 to $227.⁶

These are national averages, so ask for local quotes.

• Look over trees, shrubs, eaves and sheds in spring and early summer, while nests are tiny.³
• Avoid nests, especially those near entrances or high-traffic areas.³
• Keep trash collected. Overflowing bins attract yellowjackets and hornets in late summer.³
• Keep food and drinks covered at outdoor meals from August on, when workers want sugar.²
• Seal gaps around rooflines, windows and soffits to keep cavity nesters out.⁴
• Find out whether you are allergic to wasp venom before you deal with a nest, not during an attack.³
• Never block the entrance of a nest in a wall. Hornets can chew exit holes through drywall.⁴
• Have any nest that threatens people removed by a professional.³

Queens start nests in April or May.¹ The nests are small and hidden through spring and early summer, then big enough to see by mid to late August.³

Late in the season, the workers hunt for sugar and become nuisances at outdoor meals.³ Colonies peak at 100 to 400 workers by the end of summer, and the queens leave in fall.¹

Winter is the safe time to take a dead nest down. The colony has died and only queens survive in hiding.¹ UC IPM describes the same pattern for social wasps, with colonies growing from spring to midsummer and defensiveness rising in fall.⁵

Ohio State says baldfaced hornets are yellowjacket relatives, not true hornets. The only true hornet in the state is the non-native European hornet.^3,4 Baldfaced hornets build exposed nests in trees, shrubs or on buildings.²

The European hornet is the look-alike worth knowing. It is the largest wasp in Ohio, flies at night and nests in cavities.⁴

Ohio State Extension tells homeowners to avoid nests and have a professional remove any that threaten people.³ Anyone treating a client's property for pay needs a commercial pesticide applicator license from the Ohio Department of Agriculture.⁸ Category 10a is general pest control.⁸

UC IPM lists the bald-faced hornet, Dolichovespula maculata, among the aerial-nesting yellowjackets, and says it has white rather than yellow banding.⁵ Aerial nests hang from eaves or tree limbs with the entrance at the bottom.⁵

UC IPM says aerosols labeled for wasp and hornet nests can work, but they need extreme caution and full protective clothing.⁵ For nests that are far away or hard to reach, it suggests your local Mosquito and Vector Control District or a licensed pest control operator.⁵

The California Structural Pest Control Board has a Verify a Company or Licensee page you can use before hiring.⁹