Wasps and hornets belong to the Vespidae family. There are over 100,000 known species of wasps, and hornets are one subspecies of wasps. Hornets are distinguished from other wasps by their wider heads and larger, more rounded abdomens; they also have a different life cycle.

Anatomy

Hornets are large wasps, with some species reaching up to 5.5cm in length. True hornets are distinguished from other wasps by the wider heads and larger and more rounded abdomens. All hornets have two sets of wings.

Wasps can vary greatly in appearance among species, with some even being wingless, but their common appearance is that of a long slender body, two sets of wings, a stinger, drooping legs in flight, and an extremely thin waist between the thorax and abdomen.

Life Cycle

All hornets are social insects, i.e., they live in a colony, construct a nest, and have a hierarchy. In the spring, a fertilized queen builds a new nest high above ground and lays eggs. These initial eggs quickly hatch into female workers, who take over all aspects of building and maintaining the nest while the queen continues to lay eggs. Male drones emerge in the late summer, which quickly die after finding a queen to mate with. In autumn, all hornets with the exception of fertilized queens. In tropical latitudes, the life cycle varies more.

A hornet's nest (left) and wasp larva growing out of a caterpillar (right).

Nesting habits, hierarchical structures and life cycles vary greatly across wasp species. Most of the social temperate species construct nests that function like a hornet’s nest, although nests may be constructed low to the ground, or even underground.

Parasitic Wasps

Solitary wasps are mostly parasitoids, meaning they lay their eggs in the bodies or eggs of other insects (caterpillars, slugs etc). Most solitary wasp species are considered beneficial to humans, as their hosts and prey are usually pest insects, and they do not interfere with crop production. Some parasitoid species are even intentionally used in agricultural pest control.

Watch this National Geographic video to see the larvae of parasitic wasps.

Diet

Adult hornets mostly feed on plant matter, with a penchant for sweet substances like nectar, sap, rotten fruits, and sugary processed food. They also prey on other insects, which they then feed to their larvae.

In parasitic species, the first meals are the host bodies in which the larvae grow. Larvae are then fed insects which the adults prey on. Adult wasps can be scavengers, predatory, or subsist entirely on nectar. In some social species, the larvae produce sweet secretions which are eaten by the adults.

Sting

Hornets use stings (and bites) to kill prey and defend their nests. Unlike bees, which have barbed stingers and die after stinging, hornets can sting multiple times. The strength of the venom varies among species, but hornet stings are generally more painful to humans than other wasp species, due to a large amount of acetylcholine. Stings are rarely fatal to humans (excepting allergic reactions), but swarms of hornets can be deadly.

Closeup of wasp stinger.

Certain species of wasps (including yellow jackets and hornets) are considered the most aggressive stinging insects. In all wasps, a stinger is present on females, as it derives from a female sex organ.

Notable Species

The Asian giant hornet is the world’s largest hornet, and has a 6mm stinger which can inject large amounts of venom. Their stings has been described as feeling like a hot nail being driven into the skin, and they are estimated to kill 30-40 people annually in Japan. The European hornet is a medium-sized carnivorous species and is the most common hornet in North America.

Great Golden Digger Wasp.

Digger wasps, fairly common throughout North America, burrow into the ground or use pre-existing holes where there hatch their young and feed them paralyzed insects. The young wasps live all winter underground and emerge in the spring. Velvet ant females, technically wasps, resemble large furry ants and do not grow wings. Spider wasps, a solitary species in South America, are renowned for preying on spiders several times larger than themselves.

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