Francais | English | Espanõl

Hornet

From Wikipedia, the free encyclopedia

Jump to: navigation, search
iHornet
European hornet, Vespa crabro
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Suborder: Apocrita
Family: Vespidae
Subfamily: Vespinae
Genus: Vespa
Linnaeus, 1758
For the insect known colloquially in America as a hornet see Bald-faced hornet. Also see Australian hornet, and Hornet (disambiguation).

Hornets are the largest eusocial wasps, reaching up to 45 millimetres (1.8 inches) in length. The true hornets make up the genus Vespa, and are distinguished from other vespines 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). See wasp and bee characteristics to help identify an insect.

Contents

[edit] Geographical distribution

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 Britain to Japan the European hornet (V. crabro), and another Oriental hornet (V. orientalis) that extends via southern and central Asia to the Arabian peninsula, up to northern and eastern Africa and the Mediterranean basin (including southern Italy and Sicily). Another occurs in temperate eastern Asia Yellow hornet (V. simillima), and some tropical species also range as far north as China, Siberia, or Japan. The Asian giant hornet (V. mandarinia) is a native of temperate and tropical Asia. The European hornet V. crabro, has been accidentally introduced to North America and is present in many eastern regions.

[edit] European hornet (a temperate species)

[edit] Description

The European hornet is larger than a yellowjacket but smaller than some Asian hornet species, and has hair on the thorax and abdomen, although is not as hairy as a bee<ref>European Hornet.</ref>.

[edit] Life cycle

Image:Wespennestje Vinderhoute.JPG

Other temperate species (e.g. the yellow hornet V. simillima or the Oriental hornet V. orientalis) 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 Asian giant hornet Vespa mandarinia), it is conceivable that the cycle depends on latitude.

In Vespa 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, 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.

Image:Vespa.crabro.872.Kommentkampf.jpg

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 (called drones). Adult drones 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 survive over winter.

Hornets often live together with Velleius dilatatus.

[edit] Worker tasks

The workers accomplish a variety of tasks during the colony's lifetime. These include:

  • Foraging. Workers feed mainly on carbohydrate-rich fluids such as tree sap. They also hunt other insects, primarily flies but also other species including smaller wasps and bees; they have been known to attack dragonflies. After subduing the prey, the hornet may discard all nutrient-poor parts such as the wings, legs, head, and/or abdomen. This leaves only the thorax with the protein-rich flight muscles, which constitutes the main food of the larvae (and queen ?). On hot days, workers will bring water to the nest and deposit it on the envelope, thus cooling the interior.
  • Expanding and rearranging the nest. This includes building new combs and new cells.
  • Feeding the larvae and queen. On returning back to the nest, masticated prey flesh is fed to the larvae and queen, which have higher protein needs (respectively for growth and egg-laying) than the workers, since they no longer grow.

[edit] Relationship with humans

[edit] Myths

European Hornets are often (although wrongly) thought to be very aggressive and dangerous, and are greatly feared by some people. Some people believe that "three stings from the European hornet can kill an adult human, and that seven can kill a horse". These are common myths - a sting from a European hornet isn't any more dangerous than a wasp sting, and hornets are less aggressive than wasps. In contrast, multiple Asian hornets stings are, in fact, more dangerous.

[edit] Gentle Giants

While impressive due to their size and loud sound, European hornets are in fact much less aggressive than some of their smaller relatives notably the yellowjackets, Vespula germanica and Vespula vulgaris. When approached, European hornets can actually be seen to slowly crawl backwards and eventually flee, rather than attacking. This can make it hard to remove hornets from indoors, if they happen to come in through an open window or door. While not aggressive when encountered far from the nest, multiple workers will vigorously defend the nest if provoked.

[edit] Endangered Species and Legal Protection

Unwarranted fear has often led to the destruction of nests, leading to the decline of the species, and is often locally threatened or even endangered. European hornets benefit from legal protection in some countries, notably Germany. It is illegal to kill a European hornet or nest since 1st January 1987, with a fine up to 50,000 Euros <ref>Hornets are worthy of protection!.</ref>.

[edit] Stings

For the insect known colloquially in America as a hornet see Bald-faced hornet, and similarly for the Australian hornet, also see toxic Asian hornets species (Asian giant hornet, Yellow-legged hornet, Vespa flavitarsus etc) for important differences from the European hornet.

Hornets are not harmless, however, and the hornet sting toxicity varies greatly by hornet species - from similar to a wasp sting, to the most venomous known insects<ref name="toxicon">J.O. Schmidt, S. Yamane, M. Matsuura, C.K. Starr (1986). "Hornet venoms: lethalities and lethal capacities.". Toxicon 24 (9): 950-4.</ref>:

European hornet sting:

  • in itself is not fatal (for those without an allergy).<ref name="toxicon">J.O. Schmidt, S. Yamane, M. Matsuura, C.K. Starr (1986). "Hornet venoms: lethalities and lethal capacities.". Toxicon 24 (9): 950-4.</ref>
  • multiple stings (several hundred) may be fatal due to the amount of venom (similar to wasps and bees).[citation needed]
  • is similar to a wasp's.
  • is less toxic than a bee sting.

non-European hornet sting:

  • in itself is not fatal (for those without an allergy).<ref name="toxicon">J.O. Schmidt, S. Yamane, M. Matsuura, C.K. Starr (1986). "Hornet venoms: lethalities and lethal capacities.". Toxicon 24 (9): 950-4.</ref>
  • multiple stings (a nest full) can be fatal due to highly toxic species specific additions in the venom<ref>

P. Barss (1989). "Renal failure and death after multiple stings in Papua New Guinea. Ecology, prevention and management of attacks by vespid wasps". Med J Aust. 151 (11-12): 659-63.</ref>.

  • is more toxic than a wasp's, or bee sting, in fact...
  • Vespa mandarinia japonica is the most venomous known insect (per sting)<ref name="toxicon">J.O. Schmidt, S. Yamane, M. Matsuura, C.K. Starr (1986). "Hornet venoms: lethalities and lethal capacities.". Toxicon 24 (9): 950-4.</ref>.

All hornet sting:

  • is an allergen for people with an allergy to wasp venom - they can suffer anaphylactic shock - a condition which can be fatal, and must be treated immediately (within a few minutes) in hospital, or before.
  • the allergy (wasp allergy) is a separate allergy to bee sting allergy.
  • contains less volume of venom than a bee sting.
  • is primarily for killing insect prey.
  • is not designed for vertebrates / mammals - in contrast with a bee sting which is designed for attacking other bees and defending the nest against vertebrates / mammals (from taking honey).[citation needed]
  • is slightly more painful than a wasp's due to an extra constituent - 5% acetylcholine <ref>K. D. Bhoola, J. D. Calle, and M. Schachter (1961). "Identification of acetylcholine, 5-hydroxytryptamine, histamine, and a new kinin in hornet venom (V. crabro)". J Physiol. 159 (1): 167–182.</ref>. See Schmidt Sting Pain Index <ref>Stung - How tiny little insects get us to do exactly as they wish.</ref>.

A hornet can (similarly to wasps):

  • sting multiple times - it does not die after stinging like a bee (bees actually survive when stinging other bees).
  • bite and sting at the same time.
  • mobilise a nest to sting in order to defend itself. This situation is highly dangerous and must be avoided.

[edit] Attraction to lights and food

European hornets are attracted to lights at night, but are not attracted to human foods and food wastes. This is the opposite of the Bald-faced hornet or other yellowjacket.

[edit] Alarm Escalation

The hornet alarm pheromone is used to raise alarm of nest attack, and to identify prey, for example bees <ref>Volatile fragrance chemicals may attract unwanted attention from hornets and bees.</ref>. It is not advised to kill a hornet anywhere near a nest, as the distress signal can trigger the entire nest to attack. Remove any materials - well away from hornets - that come in contact with pheromone, either on clothes, skin or dead prey or hornet. Perfumes, and other volatile chemicals can be falsely recognised as pheromone.

[edit] Pest status

Hornets and yellowjackets prey on many insects that we consider to be pests, so are actually beneficial. They do also prey on bees, but, unlike honey bees, hornet and yellowjacket colonies die out every winter.

[edit] Actions to Avoid

  • Disturbing a nest (including vibrations and loud noises)
  • Being within a few meters or yards of a nest
  • Disturbing a hornet within a few meters of a nest
  • Blocking the path of a hornet
  • Breathing on the nest or hornet
  • Rapid air movements
  • Killing a hornet, especially near a nest
  • Never pour gasoline or petroleum down a nest hole. This is extremely hazardous and environmentally unsound.

[edit] Hornets and other Vespidae

There may be some ambiguity about the differences between hornets and other wasps of the Vespidae family, specifically the Yellowjacket. Yellowjackets are generally smaller than hornets and are bright yellow and black, whereas hornets may be darker in color - see wasp and bee characteristics.

Another major difference between yellowjackets and hornets are their food choices and aggression towards humans. In the fall, yellowjackets may be attracted to human foods and food wastes, increasing potentially aggressive contact between yellowjackets and humans. Hornets, on the other hand, tend to stick to live insects.

Some other large wasps are sometimes referred to as hornets, most notably the bald-faced hornet (Vespula maculata) found in North America. It is set apart by its black and ivory coloration. The name "hornet" is used for this and related species primarily because of their habit of making aerial nests (similar to the true hornets) rather than subterranean nests. Another example is the Australian hornet (Abispa ephippium), which is actually a species of potter wasp.

[edit] Species

V. aethale, V. affinis, V. analis, V. auraria, V. basalis, V. bellicosa, V. bicincta, V. bicolor, V. bilineata, V. binhami, V. bipustulata, V. capitata, V. cayana, V. chrysoptera, V. chrysopteraarmata, V. communis, V. condigna, V. conifera, V. consimilis, V. consobrina, V. cordifera, V. crabro, V. crabroniformis, V. crassipes, V. cribriformis, V. curvipes, V. daedalea, V. dentata, V. diadema, V. distincta, V. ducalis, V. dybowskii, V. erythrycephala, V. exotica, V. ferruginata, V. ferruginea, V. fervida, V. flavitarsus, V. florisequa, V. fluva, V. fulvipes, V. fumida, V. fusus, V. geniculata, V. guttata, V. hirsutissima, V. horticola, V. intersecta, V. italica, V. ligata, V. longicornis, V. luctuosa, V. macrocephala, V. magnifica, V. mandarinia, V. menstrua, V. minima, V. minuta, V. mocsaryana, V. mucronata, V. multimaculata, V. nigra Statz, V. nigra Geoffroy, V. ochropygos, V. ochrosticta, V. ocreata, V. ordinata, V. orientalis, V. pacicephala, V. petiolata, V. philippinensis, V. picipes, V. pilosella, V. pteropoda, V. quadripunctata, V. quinquefasciata Muller, V. quinquefasciata Schrank, V. scutellata, V. sericea, V. sessilis, V. sexmaculata, V. sexpustulata, V. simillima, V. sinuata, V. soror, V. sphaerogaster, V. taenia, V. tahitensis, V. tenebricosa, V. tesserazonia, V. trizonata, V. tropica, V. unicolor, V. usta, V. velox, V. velutina, V. verutina, V. vivax, V. xanthoptera

[edit] Notable Species

[edit] See also

[edit] Notes

<references/>

[edit] External links

Look up hornet in Wiktionary, the free dictionary.

<span class="FA" id="ja" style="display:none;" />

de:Hornissen fr:Vespa (insecte) io:Horniso lt:Vapsva ja:スズメバチ nl:Hoornaar (insect) pt:Vespa sv:Vespa (släkte) zh:胡蜂亞科

Retrieved from "http://en.wikivisual.com/index.php/Hornet"
Personal tools