Hornet | ||||||||||||||
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Scientific classification | ||||||||||||||
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Hornets are large eusocial wasps. The true hornets make up the genus Vespa, and are distinguished from other Vespids by the width of the vertex (part of the head behind the eyes), which is proportionally larger in Vespa; and by the anteriorly rounded gasters (the section of the abdomen behind the wasp waist).
Table of contents |
2 Life Cycle 3 Relationships with Humans 4 False hornets 5 External links |
The genus Vespa comprises about 20 species, most of which are
native to tropical Asia, but there is a species found across temperate
Eurasia from Great Britain to Japan (V. crabro), another (V. orientalis) that extends via southern and central Asia to the Arabic
peninsula, up to northern and eastern Africa and the Mediterranean
basin (including southern Italy and Sicily). Another occurs in
temperate Eastern Asia (V. simillima), and some tropical species
also range as far north as China, Siberia or Japan. The European
hornet V. crabro has been accidentally introduced to North America
and is present in many eastern states.
Note: this section describes the life cycle of the European
hornet, which is a temperate species. Other temperate species (e.g.
the yellow hornet V. simillima or the Oriental hornet may have similar cycles. In the case of tropical species
(e.g., V. tropica), life histories may well differ; and in species
with both tropical and temperate distributions (such as the giant
hornet V. mandarinia), it is envisionable that the cycle depends
on latitude. Such information could not be found on the web.
In V. crabro, the 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, end 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 tranforms 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 done exclusively by the queen.
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 en 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 (called drones).
Adult sexuals do not participate in nest maintenance, foraging, or
caretaking of the larvae. In early to mid-autumn they leave the nest
and mate during mating flights. The drones die shortly after the
flights. The workers and queens survive at most until mid to late
autumn; only the fertilized queens overwinter.
The workers accomplish a variety of tasks during the colony's lifetime. These include:
Hornets are often (although wrongly) thought to be very aggressive and
dangerous, and are much feared by some people. Some folk beliefs have
it that three stings from the European hornet can kill an adult human,
and that seven can kill a horse. While impressive due to their size,
European hornets are in fact much less aggressive than their smaller
relatives the yellowjackets, and their sting isn't more dangerous.
Unwarranted fear has often led to the destruction of nests, and the
species is locally threatened. It benefits from legal protection in
some countries, notably Germany.
Hornets are not harmless, however. They have a painful sting (rated a 2 on Schmidt's scale, the same as honeybees and yellowjackets) and can cause anaphylactic shock to persons with an allergy to wasp venom, a condition which can be fatal. While not aggressive when encountered far from the nest, workers will vigorously defend the nest if provoked.
Deserved or not, the hornet's reputation has inspired the naming of a number of ships, including ten named HMS Hornet (Royal Navy) and eight USS Hornet (US Navy), as well as the F/A-18 Hornet aircraft.
Some other large wasps are usually referred to as hornets, though they are not true hornets in the sense above. These include several yellowjackets, most notable the baldfaced hornet (Vespula maculata) found in North America, which is set apart by its black and ivory coloration. Another example is the Australian hornet (Abispa ephippium), actually a species of potter wasp.Geographic Distribution
Life Cycle
Worker Tasks
Relationships with Humans
Stings
Namesakes
False hornets
Vespula maculata
Whitefaced Hornet