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- updated 2013-04-26 -

Hornets: Gentle Giants!

Bad press - what is true?
Hornets are peaceful animals!


Responsible Publisher
Dieter Kosmeier
Photo Galleries and Videos
Dr. Elmar Billig
Scientific Advisor
Thomas Rickinger
Translation
Kevin Foster


The lifecycle of hornets over the year - a first overview:
Note: The exact dates for the described events usually vary to some extend from colony to colony, depending on weather conditions, region, climate, and so on ...

  • April, 25th - hornetqueen leaves her winter hideout
  • May, 10th - she settles in a nesting box and begins to build a nest
  • May, 14th - she puts her first egg down
  • May, 24th - hatch out of the first larva
  • June, 7th - the first larva begins its metamorphosis
  • June, 12th - hornetqueen is attacked by an usurper
  • June, 21st - eclosion of the first worker
  • June, 23d - first flight of the first worker
  • June, 29th - second attack by an usurper - hornetqueen has now got 4 workers with her, who kill the invader
  • July, 22d - a bird nesting box is now too small for the hornetnest (that consist of 4 combs with about 180 workers). Workers start to fly out for searching a new place for the nest.
  • July, 26th - beginning of the building of a new nest in a new place. This process is called relocation.
  • August, 5th - the queen begins to put eggs down, witch will become males and females (young queens) 1)
  • August, 14th - description of the "royal court" behavior
  • August, 15th - eclosion of the first adult males
  • August, 31st - eclosion of the first queen-larvae
  • October, 8th - hornetqueen begins to be neglected by workers and suffers from malnutrition 2)
  • October, 15th - death of the founder queen
  • October, 16th - mating ; beginning of the hibernation of the young queens 3)
  • November, 5th. The last worker of the colony dies during a frosty autumn night 4)

    1) Rearing of males starts earlier than queens, usually by the end of July or the first week of August.

    2) The demise of the old queen already begins with the eclosion of the first gynes in mid-
    September.

    3) Mating flights take place on sunny days from mid-
    September to the end of October.
       The young gynes seek hibernation quarters immediately after mating.

    4) Depending on the climatic conditions during the autumn this event may take place several weeks
        earlier, e.g. in northern
    Germany.


...listen to them here!

 click on thumbnails to enlarge the images 

The majority of people consider hornets highly dangerous and their presence often causes fear and panic. This arises due to exaggerated stories of hornets attacks and the effect of their stings. "Seven hornet-stings kill a horse, three an adult and two a child ". Such neighbourhood myths, held for generations, have led to the hornet becoming quite rare in many area of Germany, due to merciless human pursuit. Indeed in many regions of Central Europe, the hornet is threatened with extinction!

Hornet (Vespa crabro, Linnaeus 1758) with their aposematic (warning) yellow-black colouring. Shown are their large, highly sensitive main eyes. These are supported by three ‘simple’ eyes, so called "Ocelli", which are thought to be horizon detectors, arranged in a triangle (see the right picture)
Hornet (Vespa crabro) with their salient yellow-black colouring  Head of a hornet  Ocelli; Foto: Dr. Elmar Billig

Description
The largest European wasp; the female measures 25 to 35 mm long, males and workers are smaller. In males, the antennae have 13 segments, while females have 12. The male abdomen is composed of 7 visible segments, while that of the female has 6; females are equipped with an ovipositor. Eyes are deeply indented, shaped like a C. Wings are reddish-orange, the petiolated abdomen is orange striped with brown.

Hornets belong to the order or group Hymenoptera. They are closely related to ants and bees, which are also in the same order. Hymenoptera means joined wings or married wings; Hymen = god of marriage, ptera = wings. The hind wings join to the fore wings with a row of tiny hooks (called hamuli).

Like most nest building insects, hornets will defend their colony when they consider it threatened. Therefore, the behaviour of hornets must be roughly divided into two catagories:

  1. That in close vicinity to the nest (radius by 2-3m)

  2. That outside of the nest area.

In the presence of a hornet, four things should be avoided: rapid movements, blocking the flight path, vibrating or breathing on the nests.

With care and calm it is quite possible to study the intimate life of hornets without being stung.

a peaceful hornet; Photo: Dr. Elmar Billig

Outside of the nest area hornets never attack groundlessly. Few people realise that hornets are amazingly peaceful animals, even shier than honey bees, which prefer to evade conflict. Scientifically it has been shown that stings of hornets are not more dangerous than bees and wasps. It is their considerable size (queen to 35mm) and loud flight noises that induce unnecessary fears. Those striking out in fear are those that may be stung.

Dr. Elmar Billig with a peaceful hornet

For most people a hornet sting represents no special danger. Hornet poison is not more toxic than bee or wasp poison!

Some scientific results: Bee poison is chemically and toxically very well investigated, since it is easy to obtain. LD50, the poison component that leads to 50% of cases of death in lab mice, amounts to 6mg poison per kg body weight for bee poison. Reports for hornet poison range from 10mg/kg (HABERMANN 1974) to 90mg/kg (KULIKE 1986), around 1.7 – 15 weaker than honeybees! (Sources of the scientific results Kulike / Habermann)

the stinger (Photo Dr. Elmar Billig)

Unlike bees, the poison of wasps and hornets is not intended for use against vertebrates (like us) alone. Bees are nectar collecting animals, but wasps and hornets are hunters of insect prey. With several kilograms of honey in an average bees nest, the primary role of the bee sting is to defend the colony against sweet-toothed attackers, ranging from the mouse through badgers to brown bears and humans.

the stinger (Photo Dr. Elmar Billig) Wasps have substantially fewer such natural enemies.

This explains the autotomous sting of the honey bee, a bee will lose its sting and its life stinging a vertebrate. What it gains is the injection of additional poison from the poison gland which continues to pump on its release. Wasps and hornets use their sting to kill troublesome insect prey. They cannot afford to be wasteful, as they need to be able to sting repeatedly, injecting just about 0.16 - 0,19 mg poison (oven-dry mass). We, hence, have more to fear in the sting of the bee than the hornet!

However, the hornet sting contains 5% acetylcholine which stimulate pain fibres more than stings of other wasps and bees. So the sting of a hornet may be a little bit more painful.

Guard at the nest entrance
Guard of the nest input of a "hornet castle"

Sting advice: cooling the area is soothing, as for bee stings. In exceptional cases hornet stings, like other insect stings, can induce an allergic reaction, arising from an overactive immune system. These reactions begin with considerable swelling and redness in the affected area. In the case of a reaction you should see a doctor to be on the safe side.

The hornet lives throughout most of Europe, but is never found north of the 63rd parallel. It is also found in Asia, the United States and Canada. Meanwhile also in Guatemala.

The hornet lives throughout most of Europe, but is never found north of the 63rd parallel. It is also found in Asia, the United States and Canada

There are several geographic color forms of the Hornet found worldwide:
Sources:
J. Bequaert. The color forms of the common hornet, Vespa crabro Linnaeus. Konowia (1931) 10, 101-109.

V. Dubatolov, J. Kojima, J. M. Carpenter, A. Lvovsky. Subspecies of Vespa crabro in two different papers by Birula in 1925. Entomological Science (2003) 6, 215-216

J.M. Carpenter, J. Kojima. Checklist of the species in the subfamily Vespinae (Insecta: Hymenoptera: Vespidae). Natural History Bulletin of Ibaraki University 1 (1997), 51-92.

  • Vespa crabro crabro Linnaeus, 1758

  • Vespa crabro vexator Harris, 1776

  • Vespa crabro germana Christ, 1791

  • Vespa crabro crabroniformis Smith, 1852

  • Vespa crabro oberthuri du Buysson, 1902

  • Vespa crabro flavofasciata Cameron, 1903

  • Vespa crabro altaica Pérez, 1910

  • Vespa crabro caspica Pérez, 1910

  • Vespa crabro chinensis Birula, 1925

Technically, Vespa crabro is the only hornet in North America, but it did not originate here; it was introduced from Europe. The European hornet was first reported in North America about 1840 in New York state. Since then, it has spread to most of the eastern United States, reaching as far west as Louisiana and the Dakotas. Nowadays it is found in the northeastern quarter of the United States; ranging from Canada, Ontario, North Carolina, Texas, Tennessee and south through the eastern and central US, with scattered sightings extending west of the Mississippi River.

The European hornet "Vespa crabro" is the largest vespine in North America. It is the only vespine in the new world that is brown with yellow markings. The vertex of the Vespa crabro is much larger than wasps of the genera Vespula and Dolichovespula.

head of a hornet (Photo: Dr. Elmar Billig)

Even though Vespa crabro is rarer than the various species of Vespula and Dolichovespula, it is not in danger of extinction in the USA. It seems to be doing well in its range there. Generally, it is considered to be a forest species in the USA. This means that it is rare to find a Vespa crabro colony near human habitats (unless it is out in the country). So, human contact with colonies of this particular species is uncommon in the USA. Though it does happen on occasion. However, few reactions to stings have been reported there.

Common names for Hornets in other countries:
Germany: Hornisse; Spain: Abejorro, Avispon; France: Frelon, Guêpe frelon, Guichard; Italy: Calabrone;
Poland = Szerszeń; Portugal: Vespa grande; Netherlands: Hoornaar; Sweden: Bålgeting; Denmark =  Stor gedehams; Latvia / Lettonie: sirsenis oder irsis; Russia = scherschen; Finland = herhiläinen, herhiläiset

Hornet; Photo: Dr. Elmar Billig

USA: Giant Hornet, European Hornet, Old World Hornet. Vespa crabro is there also commonly called the "Brown Hornet", and is sometimes mistakenly referred to as the "Japanese Hornet". This is the largest and, technically, the only true hornet found in the United States. It is not the same wasp as the "Bald-Faced-Hornet" or the "Yellow Hornet".

 


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