Hornet

Hornets are large, social wasps belonging to the genus *Vespa*. They are the largest members of the eusocial wasps, a group known for living in organized colonies.

While they look similar to yellowjackets, hornets are distinguished by the relatively large top margin of their heads. There are 22 recognized species within the *Vespa* genus. Most of these species live in the tropical regions of Asia. However, the European hornet (*Vespa crabro*) has a much wider distribution. It lives throughout Europe, Russia, North America, and northeastern Asia.

Many insects are incorrectly called hornets due to their appearance or behavior. In North America, the bald-faced hornet is actually a type of yellowjacket from the genus *Dolichovespula*. It is named a hornet because it builds aerial nests rather than underground ones. Similarly, the Australian hornet is actually a species of potter wasp. There are also "night hornets" in the genus *Provespa*, which are nocturnal Asian wasps. These naming differences can cause confusion when studying the family Vespidae. Understanding these distinctions helps scientists correctly classify these different stinging insects.

A hornet colony follows a specific life cycle that begins in the spring. A fertilized female, known as the queen, founds the nest.

She selects a sheltered location, such as a dark, hollow tree trunk. The queen builds horizontal layers of cells called combs by chewing wood into a papery pulp. She lays an egg in each cell. After five to eight days, the egg hatches into a larva. The larva undergoes five stages of development over two weeks. During metamorphosis, the larva spins a silk cap and transforms into an adult.

Once the first generation of female workers hatches, they take over all tasks except egg-laying.

As the colony grows, the workers add more combs and build an outer envelope. This envelope covers the cells, leaving only an entry hole. In temperate areas, the nest dies during the winter. During this time, lone queens hibernate in insulating material like leaf litter. In the tropics, however, some nests may last all year. At the peak of the population in late summer, a colony can reach 700 workers. The queen then produces reproductive individuals. Fertilized eggs become females called gynes, while unfertilized eggs become males, or drones.

The males leave the nest in autumn for nuptial flights to mate.

Adult hornets have a dual diet consisting of sugars and proteins. They consume nectar and sugar-rich plant foods like sap or rotting fruit.

They often gnaw holes in fruit to reach the pulp. To feed their larvae, adults hunt other insects. They use strong mandibles and venomous stings to kill prey like honey bees or grasshoppers. The adults do not eat the prey themselves. Instead, they masticate the insects and feed the remains to the larvae. This protein-rich diet is essential for the growth of the developing brood.

Hornets are highly defensive and use chemical signals to protect their nests. When threatened, they release an attack pheromone to mobilize the colony.

In the Asian giant hornet (*Vespa mandarinia*), three chemicals work together to increase aggression. These include 2-pentanol, isoamyl alcohol, and 1-methylbutyl 3-methylbutanoate. In the European hornet, the main compound is 2-methyl-3-butene-2-ol. These scents can be triggered by a dying hornet near the nest. Even certain food flavorings, like banana or apple, can trigger an attack. This chemical defense makes a disturbed nest very dangerous to humans.

The stings of hornets can be quite significant due to their chemical makeup. Hornet venom contains a high concentration of acetylcholine, about 5%. This makes their stings more painful than those of typical wasps. Unlike honey bees, hornets do not die after stinging. Their stingers are finely barbed, allowing them to be withdrawn easily for repeated stings.

The toxicity varies greatly between species. The Asian giant hornet is among the most venomous insects in the world. In Japan, its stings are thought to cause 30 to 50 human deaths every year. In China, 42 people died from hornet stings between July and September 2013. While a single sting is rarely fatal to non-allergic people, multiple stings can cause organ failure.