What to Know About Hornets

Medically Reviewed by Dany Paul Baby, MD on January 17, 2023
5 min read

Hornets are flying insects that feed on bugs. True hornets are less aggressive than some wasp species, but they can still be a nuisance and are dangerous for some people. 

Hornets are a type of wasp that belongs to the Vespa genus. Wasps and hornets are sometimes called yellowjackets, but these are another species of wasps that usually build a nest in the ground or walls and attics of buildings. 

European hornets. The European hornet, species Vespa crabro, is native to Europe and Asia and is now widespread across North America. This hornet is a large social woodland wasp, usually the largest species in the area, and the only true hornet commonly found in the United States.

Northern giant hornet. Known as the species V. mandarinia, the Northern giant hornet is native to Japan and India. It’s an uncommon hornet in the U.S. but was recently found in Washington State in 2019. It is the biggest hornet in the world, measuring 2 inches long. 

Baldfaced hornet. Despite its name, the baldfaced hornet is a different species, Dolichovespula maculata, and technically isn’t a hornet. Instead, it’s considered a type of yellowjacket, even though it’s black with white markings. At 0.75 inches long, these so-called hornets are slightly larger than a yellowjacket but smaller than a true hornet.

It’s easy to confuse yellowjackets and hornets, but there are key differences in size and color. As it sounds, yellowjackets have black bodies with yellow bands and are small, only about half an inch long. 

A true European hornet is brown and orange or yellow. It has a reddish-brown thorax and an abdomen with a black upper section, wide yellow bands, and rows of black teardrops on the bottom. 

Hornets are much bigger insects, around 1.5 inches long, and the queen is the largest of the colony, about 2 inches long. Hornets have smooth stingers and can sting multiple times in a row.

True European hornets are woodland insects. They build nests inside hollow trees, usually about 6 feet above ground or higher, but sometimes in barns, sheds, or walls of a house or attic. 

The queen emerges from hiding in the spring and builds a tan, paper nest from chewed wood and saliva. She lays her eggs in the first cells of the nest, which will hatch and become worker hornets.

These hornets take over building the nest, caring for other young hornets, and hunting. If the nest is exposed or unprotected, worker hornets will cover it with a brown envelope. 

Each nest only survives until fall, and then all the hornets die. A few mated queens leave the nest, find somewhere to shelter over winter, and then emerge again in the spring to start over in a new nest.

Hornets are predators. They hunt and catch insects like bees, flies, and grasshoppers and feed those to young hornets or growing larvae. They feed on sweet tree sap or chew holes in fruit and feed on the juices during the fall.  

European hornets are dangerous if you’re allergic to bee or wasp stings, but they're generally not aggressive unless you disturb them or they need to protect the nest. Unlike other wasps or stinging insects, these hornets fly at night and are attracted to light, so they might try to get into your house.  

Do hornets sting? European hornets sting, but it's often only as painful as a honeybee sting. In most cases, a hornet sting will get better within a few hours and isn’t a concern unless you’re allergic to wasp stings or are stung multiple times. 

The best way to avoid a sting is to stay calm if you notice a hornet near you. Most of the time it will fly right past you without bothering you. If you swat at it, you will irritate it, and it will respond by stinging. 

Hornet sting treatment. If a hornet stings you, wash the area with soap and water and remove the stinger. You can wipe gauze or scrape your fingernail over the site, but don’t squeeze it or use tweezers. Then apply ice to lower swelling and help with the pain. It should get better within a few hours. 

If you have symptoms, use your epi-pen if you have one, and go to the emergency room for medical attention. Signs and symptoms of a hornet sting allergy include:

  • Hives, swelling, and itching 
  • Wheezing and trouble breathing
  • Stomach cramps, vomiting, and diarrhea
  • Throat swelling, trouble swallowing, or coughing

It's best to leave the hornet nest alone unless you find one in your home or near busy areas. The frost will kill off the hornets in the fall, and they won’t return to the nest again. If you need to kill the colony, hire a professional or use a hornet spray.

Spray the nest. Use a wasp and hornet aerosol spray with a jet spray of 10 to 15 feet. Aim the spray into the nest and spray for 5 to 10 seconds. Then move away quickly to avoid any wasps that might come out. 

This is best done in the evening when the hornets are less active. Make sure there’s enough light to see without a flashlight because the hornets will fly toward a light. Repeat the treatment the next day. Once the hornets are dead, remove the nest from the building walls and attics. 

Hire a professional. If you’re unsure what type of wasp you have, you’re nervous about being stung, or you have a huge nest, hire a professional.

Hornets are a type of woodland wasp. They are a few species, but the European hornet is most common in the United States. They live in hidden nests inside trees but sometimes in building walls or attics. Hornets stings can be dangerous if you’re allergic or stung repeatedly. While you can leave a nest alone, lots of people choose to get rid of them to avoid nuisance stings.