Hornets!

The European hornet has been accidentally introduced to North America and is present in many eastern regions.

The European hornet is the largest European eusocial wasp, commonly known simply as the "hornet". This is not to be confused with the colloquial use of hornet for the bald-faced hornet, or other yellowjackets in other countries. The queen measures 25 to 35 mm long, males and workers are smaller. In males, as in most members of the Aculeata, the antennae have 13 segments, while in females there are only 12; also as in other aculeates, the male abdomen has seven visible segments, while the female has six; females possess an ovipositor modified into a sting which is not barbed.

This species is not particularly aggressive except when defending the nest, and care must be taken when in proximity, as the stings are quite painful. As with most stinging insects, they will sting in self-defense when grabbed or stepped on.

The European hornet nest is founded in spring by a fertilized female, known as the queen. She generally selects sheltered places like hollow tree trunks. She builds a first series of cells (up to 50) out of chewed tree bark. The cells are arranged in horizontal layers named combs, each cell being vertical and closed at the top. An egg is then laid in each cell. After 5-8 days it hatches, and in the next two weeks the larva undergoes its five stages. During this time the queen feeds it a protein-rich diet of insects. Then the larva spins a silk cap over the cell's opening, and during the next two weeks transforms into an adult, a process called metamorphosis. Then the adult eats her way through the silk cap. This first generation of workers, invariably females, will now gradually undertake all the tasks that were formerly carried out by the queen (foraging, nest building, taking care of the brood, etc) with one exception: egg-laying, which remains exclusive to the queen.

Life history
As the colony size grows, new combs are added, and an envelope is built around the cell layers, until the nest is entirely covered, with the exception of an entry hole. At the peak of its population the colony can reach a size of 700 workers. This occurs in late summer.

At this time the queen starts producing the first reproductive individuals. Fertilized eggs develop into females (called "gynes" by entomologists), unfertilized ones into males (sometimes called "drones"). Adult males do not participate in nest maintenance, foraging, or caretaking of the larvae. In early to mid-autumn they leave the nest and mate during "nuptial flights". Males die shortly after mating. The workers and queens survive at most until mid to late autumn; only the fertilized queens survive over winter.

The Bald-faced hornet (or White-faced hornet), is not a true hornet at all. It belongs to a genus of wasps called yellowjackets in North America, and is more distantly related to true hornets like the Asian giant hornet or European hornet, but the term "hornet" is often used colloquially to refer to any vespine with an exposed aerial nest. To be more precise, it is an aerial-nesting yellowjacket

Every year young queens that were born and fertilized the previous year start a new colony and raise their young. The workers expand the nest by chewing up wood that mixes with a starch in their saliva, which they spread with their mandibles and legs to dry into paper. The workers also guard the nest and collect nectar and arthropods to feed the larvae. This continues through summer and into fall. As winter approaches, the wasps die, except for young fertilized queens which hibernate underground or in hollow trees. The nest is generally abandoned by winter, and will most likely not be reused. When spring arrives the young queens emerge, and the cycle begins again.

Bald-faced hornets visit flowers, especially in late summer, and can be minor pollinators.

Like other social wasps, Bald-faced Hornets have a caste system made up of the following:

Queens - Fertile females which begin the colonies and lay eggs
Workers - Infertile females which do the manual labor
Drones - Males, which have no stingers, and are born from unfertilized eggs.

The Asian giant hornet is known colloquially as the Yak Killer Hornet, is the world's largest hornet, native to temperate and tropical Eastern Asia. Its body length is approximately 50.8 mm (2.0 in), with a wingspan of about 76 mm (3 in). Queens may reach a length of 55 mm (2.2 in). Due to its size, it is known in Japan as Suzume-Bachi or Sparrow-Bee.

The head of the hornet is orange and quite wide in comparison to other hornet species. The compound eyes and ocelli are dark brown, and the antennae are dark brown with orange scapes. The clypeus (the shield-like plate on the front of the head) is orange and coarsely punctured; the posterior side of the clypeus has narrow, rounded lobes. The mandible is large and orange with a black tooth (inner biting surface).

The thorax and propodeum (the segment which forms the posterior part of the thorax) of the Asian giant hornet has a distinctive golden tint and a large scutellum (a shield-like scale on the thorax) that has a deeply-impressed medial line; the postscutellum (the plate behind the scutellum) bulges and overhangs the propodeum. The hornet's forelegs are orange with dark brown tarsi (the distal - furthest down - part of the leg); the midlegs and hindlegs are dark brown. Wings are a dark brownish-gray. The tegulae are brown.

The gaster (the portion of the abdomen behind the thorax-abdomen connection) is dark brown with a white, powdery covering; with narrow yellow bands at the posterior margins of the tergite, the sixth segment is entirely yellow.

The stinger of the Asian giant hornet is about 6 mm (¼ in) in length, and injects an especially potent venom that contains, like many bee and wasp venoms, a cytolytic peptide (specifically, a mastoparan) that can damage tissue by stimulating phospholipase action, in addition to its own intrinsic phospholipase. Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling "like a hot nail being driven into my leg."

An allergic human stung by the giant hornet may die from an allergic reaction to the venom; but the venom contains a neurotoxin called mandaratoxin which can be lethal to people who are not allergic if the dose is sufficient. About 70 people die each year in Japan after being stung by giant hornets.[5]

A few interesting notes on Vespa mandarinia's venom and stinger:

The venom contains at least eight distinct chemicals, some of which damage tissue, some of which cause pain, and at least one which has an odor that attracts more hornets to the victim.

The venom contains 5% acetylcholine, a greater concentration than is present in bee or other wasp venoms. Acetylcholine stimulates the pain nerve fibres, intensifying the pain of the sting.

Vespa mandarinia uses its large crushing mandibles, rather than its sting, to kill prey.

The venom of the Asian giant hornet is more toxic than that of most other bees or wasps, giving this species one of the greatest lethal capacities per colony.

The enzyme in the venom is so strong that it can dissolve human tissue.

Like all hornets, V. mandarinia has a barbless stinger, allowing it to sting repeatedly.

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Much of the information used here has been researched from Wikipedia, the free encyclopedia.

All text is available under the terms of the GNU Free Documentation License.