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Interesting Facts About Hornets: Large Wasps With Paper Nests

Linda Crampton is a writer and former science teacher with an honors degree in biology. She enjoys writing about science and nature.

What Are Hornets?

Hornets are large and interesting wasps with complex behaviors. They are social insects and live in highly organized colonies. The colony builds an intricate nest from a papery substance made when the hornets chew wood and mix it with their saliva. The resulting structure is a wonderful feat of engineering and is both lightweight and strong.

Hornets eat plant matter and are also predators of other insects. They will sting humans if they're disturbed, but most are not aggressive at other times. While the sting of some species is no more dangerous than the sting of a common wasp, in other species the sting is very painful and may also be dangerous.

Hornets are widespread and are found in Asia, Europe, Africa, and North America. At the moment, one species of hornet is creating a serious problem for humans. The Asian hornet or Asian predatory wasp is native to China but has colonized other countries as an invasive species. The species is of great concern since it kills bees. A group of Asian hornets can rapidly destroy a honeybee colony, sometimes within a few hours.

A western yellow jacket queen (Vespula pensylvanica) in North America: yellow jackets are a type of wasp but aren't hornets.

A western yellow jacket queen (Vespula pensylvanica) in North America: yellow jackets are a type of wasp but aren't hornets.

What's the Difference Between a Hornet and a Wasp?

  • A hornet is a type of wasp.
  • The insect family known as the Vespidae contains hornets, yellow jackets (which are the most familiar type of wasp for many people), paper wasps, potter wasps, and pollen wasps.
  • True hornets belong to the genus Vespa within the family Vespidae. The genus is the first part of the scientific name for a living thing. Hornets aren't native to North America, but the European hornet (Vespa crabro) has been introduced to the continent.
  • Yellow jackets belong to either the genus Vespula or the genus Dolichovespula in the family Vespidae.
  • The bald-faced hornet of North America is actually a type of yellow jacket, although it has black and white markings instead of the black and yellow markings of the common yellow jacket wasps. Its scientific name is Dolichovespula maculata.

Hornet Nests

Hornet nests are usually aerial and are found in treetops, under roofs or decks, in sheds or garages, in hollow tree trunks, or in other areas that are raised off the ground. The nest is large and is shaped like a football. It contains horizontal combs, which hang in tiers and are connected to each other. Each comb contains many chambers or cells for eggs and larvae. The nest is often surrounded by layers of papery material that insulate the structure.

Some nests are free-hanging. A stalk called a petiole attaches the nest to an object such as a tree branch. Other nests are built in an enclosed space that provides support.

Some people like to collect hornet nests so that they can examine and admire their intricate structure. It's very important to do this after all the insects have left at the end of the season and not before. Despite their larger size, many hornet species (though not all of them) are less aggressive than the common yellow jacket wasps. All hornets become aggressive if their nest is being attacked, however.

If you need to get an active or possibly active hornet nest removed, it's best to ask a professional pest controller to do this. He or she will know how to deal with any living insects that are present in the nest.

A hornet nest that has been broken open and partially rebuilt, showing the horizontal combs and the papery outer layers of the nest

A hornet nest that has been broken open and partially rebuilt, showing the horizontal combs and the papery outer layers of the nest

Composition of the Colony

The only member of the hornet colony that reproduces is the queen. Most hornets in the colony are workers, which are sterile females. The workers make the nest after it has been started by the queen and the workers have developed from the eggs that she laid. Workers also feed the young and protect the colony from danger.

Late in the season, males and new queens are born. A male mates with a new queen and dies soon afterwards. In at least some species, a paired male and queen come from different colonies.

In temperate climates, a hornet nest is inhabited for only one year. The worker bees, the males, and the season's queen die in the autumn. The new queens survive. They spend the winter hiding under loose tree bark, in the soil, or even in a building.

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In this article, I describe three species of hornets. Their common names can be confusing. The species are introduced in the table below.

Three Interesting Species of Hornets

Scientific NameCommon NameNotes

Vespa crabro

European hornet

Found in Europe, Asia, and North America

Vespa mandarinia

Asian giant hornet

One subspecies is called the Japanese giant hornet

Vespa velutina

Asian hornet

Also called the Asian predatory wasp

The European Hornet (Vespa crabro)

In the spring, the new queens of the European hornet emerge from their winter hiding places and find a place to build a nest. They chew wood and mix it with saliva to form a light but strong construction material that is similar to paper mache.

The nest is generally built in an area that provides support for the nest instead of being free-hanging. Nests can be found in hollow cavities in tree trunks and in attics, barns, and sheds. They may even be built in cavities in walls.

European Hornets Guarding Their Nest Entrance

The Queen, Larvae, Pupae, and Workers

  • The European hornet queen makes the first cells of the nest and lays a fertilized egg in each one. After about five to eight days, the eggs hatch into young forms of hornet known as larvae or grubs.
  • The queen feeds the larvae a paste made of her saliva and insects that she has chewed. She also continues to make new cells and to lay eggs.
  • At about two weeks of age, each larva makes a silk cap to fit over the top of its cell. Inside the sealed cell, the larva turns into a pupa.
  • Inside the pupa, the young hornet changes into an adult worker bee. The worker then emerges from its cell and takes over the jobs of building the nest and feeding the larvae.
  • The larvae release a sweet secretion which the workers eat. The secretion contains amino acids as well as sugars. It provides the workers with energy and encourages them to keep feeding the grubs.
  • Once enough workers have emerged from the pupae, the queen's sole job is to lay eggs.
  • European hornets fly during the night as well as during the day to collect food.
  • The hornets prey on other insects, including flies, beetles, grasshoppers, bees, and yellow jackets.
  • The workers sometimes damage trees because they strip the bark to get to the sap. They can also damage fruit crops. However, they may help humans by killing harmful insects.

European Hornets Feeding on Tree Sap in North America

The Drones and New Queens

  • In late summer, males (or drones) are produced from unfertilized eggs.
  • In the fall, new queens develop from fertilized eggs.
  • The new queens leave the colony and mate with males from other colonies.
  • The queens store the sperm in their bodies until it's needed to fertilize eggs in the spring. They find a place to hide and become dormant over the winter.
  • When the sperm starts to become active in the spring, fertilization begins. The queen is able to produce a new colony from the stored sperm.

The Asian Giant Hornet (Vespa mandarinia)

The largest hornet in the world is the Asian giant hornet, or Vespa mandarinia. It has a body length of about two inches, a wingspan of about three inches, and a stinger that is about a quarter of an inch long. The Japanese giant hornet is a subspecies of the Asian giant hornet and has the scientific name Vespa mandarinia japonica. Unlike other hornets, the Asian giant hornet often forms underground nests in cavities such as tunnels created by rodents.

Native bees in Japan have developed a fascinating way to defend themselves against the much larger hornets. When a hornet scout finds a honeybee colony, it releases communication chemicals called attack pheromones. If the scout returns to its own colony, the pheromones will attract the other hornets and trigger their attack on the bees.

The honeybees can detect the pheromones released by the hornet scout. They allow the hornet to approach and lure it into their hive. The bees then surround and cover the unfortunate hornet, forming a "bee ball".

The honeybees in the bee ball vibrate their wing muscles rapidly, raising the temperature around the hornet to as high as 115°F (46°C). The crowd of bees also releases a large amount of carbon dioxide. The combination of high temperature and high carbon dioxide concentration kills the scout, preventing it from communicating with its colony. Bees introduced to Japan from another country (such as European honeybees) haven't developed the overheating behavior and are often slaughtered by attacking hornets.

Japanese honeybees in a ball around two hornets: the ball heats and kills the hornets

Japanese honeybees in a ball around two hornets: the ball heats and kills the hornets

Effects of the Insects on Humans

The sting of the Asian giant hornet is very painful for humans and is potentially dangerous. The venom is powerful and contains chemicals that can destroy human tissue and interfere with nerve action. A significant number of people in Japan die from giant hornet stings every year. The insect has been given the nickname “murder hornet” by the popular press.