The European hornet (Vespa crabro) is the largest eusocialwasp native to Europe. It is also the only true hornet (genus Vespa) found in North America, having been introduced to the United States and Canada from Europe as early as 1840.[1][2] Vespines, such as V. crabro, are known for making intricate paper-like nests out of surrounding plant materials and other fibers.[3] Unlike most other vespines, reproductive suppression involves worker policing instead of queen pheromone control, as was previously thought.
This species stings in response to being stepped on or grabbed, but generally avoids conflict. It is also defensive of its nest and can be aggressive around food sources. Care should be taken when they are found in these circumstances, as they may sting without warning. European hornets are largely carnivorous and hunt large insects such as beetles, wasps, large moths, dragonflies, and mantises.[4][5][6][7][8] They also feed on fallen fruit and other sources of sugary food.[2] Mutual predation between medium-sized hornets and the Asilidae (robber flies) is often reported.
Taxonomy
The European hornet is a true hornet (genus Vespa), a group characterized by eusocial species. The genus is in the subfamily Vespinae, members of which are known for chewing up their food to feed it to their young, as well as chewing up paper-like materials to make their nests. According to a recent phylogenetic study, its closest relative is Vespa dybowskii.[9]
V. crabro form "vexator" – British form with an almost yellow head
The former subspecies of V. crabro (e.g.[10][11]) are now considered to be geographic color forms; while a history exists of recognizing subspecies within many of the Vespa species, the most recent taxonomic revision of the genus treats all subspecific names in the genus Vespa as synonyms, effectively relegating them to no more than informal names for regional color forms.[12]
Description
The eyes of V. crabro are deeply indented and shaped like a "C". Its wings are reddish-orange, while the petiolate abdomen is striped with brown and yellow. It has hair on the thorax and abdomen, although the European hornet is not as hairy as most bees.[13] Due to this coloration and abdomen pattern, V. crabro is often mistaken for the Asian giant hornet. Typical mass size for the European Hornet is 477.5±59.9mg.[14] Workers average around 25mm (1.0in) in length, while the larger queens can reach up to 35mm (1.4in).[2] This is significantly larger than most common wasps (such as Vespula vulgaris), but smaller than the Asian giant hornet. Females are typically larger than males in both size and mass. However, male abdomens have seven segments, whereas female abdomens have six.[1] There is a cerebralganglion, two thoracic ganglia, and five abdominal ganglia.[15] Only females possess a stinger, it is a modified egg laying device (ovipositor): males cannot sting. The antennae of males are slightly longer, with 13 segments compared to twelve segments in females.[1]
Nests
Individuals typically live in paper nests, which consist of a pedicle (a paper comb on the inside), an envelope, and a single entry hole on the outside. Materials such as twigs, branches, and other available plant resources are broken up, chewed, and shaped into a nest by the workers. These pieces are not uniform in shape, but are glued together very closely. Because social wasps generally prefer to build nests in the dark, envelopes are commonly found surrounding the nests to make them dark if the colony could not locate a dark crevice in which to build.[3] The rove beetleVelleius dilatatus is commensal with the European hornet, living much of its life in the detritus of the nest.[16]
Nest
Construction
The nest is composed of a paper-pulp mixture created by female workers chewing up dead bark, trees, or plant matter from nearby surroundings and mixing it with their saliva. To build the actual comb, saliva is used as a cement to piece together organic and inorganic materials that are readily available to the colony. This cement not only holds together the comb, but also protects the comb from being damaged by water. It provides a protective barrier to help protect the colony from wind or other harsh weather conditions. Available resources, location, and amount of mastication affect the final nest's appearance, so much variation is seen among the nests of V. crabro.[3]
Physical and chemical composition
Minerals such as titanium, iron, and zirconium are commonly found in the soil and they, too, become part of the comb walls. The average dry weight of the nest is about 80.87 grams (2.853oz). Cells in the paper comb are typically 8–9 millimetres (0.31–0.35in) long and 4–5 millimetres (0.16–0.20in) in diameter. Analysis of the composition of nests in northern Turkey revealed oxygen, carbon, and nitrogen as the main elements, while trace amounts of silicon, calcium, iron, and potassium were found, although none of aluminium, magnesium, or sodium, providing evidence that European hornets use the surrounding soil as a resource in building their nests. The ratio of fibrous material to actual saliva affects the nest's ability to absorb water, and thus how well its inside stays dry. In the nests studied in Turkey, fiber content was 23%, with 77% hornet saliva. This combination resulted in optimal water absorption capacity.[3]
Distribution
As the name "European hornet" implies, V. crabro originated in Eurasia. Nests historically ranged from Japan to the United Kingdom. However, Saussure reported that V. crabro was introduced to North America in the mid-19th century, where it is now well established. In 2010, they were found as far south as Guatemala. The few nests in Guatemala were thought to be recent, accidental introductions, as they were the first to be documented.[17]
Life cycle
Life history
V. crabro prefers to build nests in dark places, usually hollow tree trunks. After the site has been chosen, the queen lays eggs in the combs inside the nest. The workers dispose of any eggs that are not laid by their queen; this behavior is called worker policing. Based on laboratory data, the average rate of egg-laying is 2.31 eggs per day. However, in this same nest, cell construction rate was only 1.63 cells per day.[18]
V. crabro colonies seasonally change strategies of obtaining food for both the larvae and adults. In April, when the queen normally lays her eggs, the workers actively go out and forage. Later, typically around the fall season, the foraging workers switch to scavengers. Instead of putting forth the effort to catch food sources, the workers try to take what is more easily available. For example, European hornets have been seen hovering around garbage cans and picnic areas in the fall.[19]
Worker policing
Very few workers lay eggs in healthy V. crabro colonies. While only queens mate and produce fertilized female eggs, workers are capable of laying haploid male eggs. Workers are generally more closely related to male offspring of other workers than to male offspring of the queen.[20] Workers would have reproductive benefits from laying male eggs, but do not do so.[21] This was originally thought to be caused by pheromone control by the queen, but new evidence has shown that this is not the case. Workers enforce sterility on one another in a strategy known as worker policing. Workers either physically destroy worker-laid eggs or discriminate against those workers that attempt to lay eggs. Ensuring that only the queen reproduces is thought to be likely to benefit the organization and productivity of the colony as a whole, by reducing conflicts.[21]
Alarm behavior
Social hymenopteran species typically communicate with each other through behaviors or pheromones. In the European hornet, a typical alarm dance is performed outside of the nest and consists of consistent buzzing, darting in and out of the nest, and attacking or approaching the target of the alarm pheromone. The alarm pheromone is stored in, and secreted from, internal venom sacs. 2-Methyl-3-butene-2-ol is the main pheromone component that causes V. crabro to express this defensive behavior. Other pentenols and pentanols are contained within these venomous sacs, but their primary purpose is likely not to warn fellow hornets that danger is nearby, because these chemicals do not induce alarm behavior.[22]
Kleptoparasitism
European hornets have been observed to steal prey from spiders, which can be classified as an example of kleptoparasitism. This behavior was first documented in 2011 against a yellow garden spider, Argiope aurantia. A European hornet flew into the spider’s web and appeared entangled. The hornet cut free a captured insect (possibly a eumenine wasp), wrapped in silk, from the spider’s web. The spider did not attack or interfere with V. crabro while it was stealing its prey.[23] This behavior follows the pattern of most vespines' changing their foraging techniques from hunting to scavenging, especially once the autumn season begins.
Unwarranted fear of V. crabro has often led to the destruction of nests. This has led to the decline of the species, which is often locally threatened or even endangered. European hornets benefit from legal protection in some countries, notably Germany, where killing a European hornet or nest has been illegal since January 1, 1987, with a fine up to €50,000.[25] However, the highest reported fine levied in Germany for killing of wasps was €45, and experts report that fines are rarely imposed.[26][27]
Problems associated
European hornets hunt many species of insects to feed their larvae. While many of these insects are considered to be garden pests, European hornets also prey on western honey bees (Apis mellifera). However, they do not typically pose a threat to healthy western honey bee colonies, unlike the Asian hornet or Asian giant hornet, which are invasive in some parts of the world.[28] Some beekeepers in Europe may keep hornets and their nests in specially designed boxes hanging on trees, on the premise that the protection they provide against wax moths is worth the occasional bee they may prey upon.[25] European hornets tend to girdle branches, which results in dead branches.[29]
Stings: case study
Most cases of stings from V. crabro do not require medical attention, but rarely can be serious. A documented case requiring treatment displayed symptoms including tingling at the site of the sting, headaches, and shortness of breath. In the hospital, the victim was found to have a fast, irregular heartbeat with a blood pressure of 111/63. A subsequent EKG demonstrated atrial fibrillation with a rapid ventricular response. V. crabro venom contains neurotransmitters such as dopamine, serotonin, histamine and noradrenalineneurotoxin apamin, as well as enzymes phospholipase A and hyaluronidase, and proteins melittin and bradykinin. These compounds have been shown to cause episodes of tachycardia in smaller animals. The mechanism of the described attack is still undetermined, but the victim was possibly abnormally susceptible to vespine stings. Currently, the two most effective treatments for reactions are electrical cardioversion or propafenone. The victim in this case study was given an oral dose of propafenone (150mg) and his atrial fibrillation resolved.[30]
↑ V. Dubatolov; J. Kojima; J. M. Carpenter; A. Lvovsky (2003). "Subspecies of Vespa crabro in two different papers by Birula in 1925". Entomological Science. 6 (2003): 215–216. doi:10.1046/j.1343-8786.2003.00037.x. S2CID84172284.
↑ J.M. Carpenter; J. Kojima (1997). "Checklist of the species in the subfamily Vespinae (Insecta: Hymenoptera: Vespidae)". Natural History Bulletin of Ibaraki University. 1 (1997): 51–92.
↑ A.H. Smith-Pardo, J.M. Carpenter, L. Kimsey (2020) The diversity of hornets in the genus Vespa (Hymenoptera: Vespidae; Vespinae), their importance and interceptions in the United States. Insect Systematics and Diversity 4(3) https://doi.org/10.1093/isd/ixaa006
↑ Day, E. (12 March 2015). "European Hornet". Virginia Cooperative Extension. 2911-1422 (ENTO-123NP).
↑ Hoffmann, W.R.E.; Neumann, P.; Schmolz, E. (2000). "Technique for rearing the European hornet (Vespa crabro) through an entire colony life cycle in captivity". Insectes Sociaux. 47 (4): 351–3. doi:10.1007/PL00001729. S2CID17378825.
↑ Davis, M. (2011). "A hornet (Vespa crabro) steals prey from a spider (Argiope aurantia)". Southeastern Naturalist. 10 (1): 191–192. doi:10.1656/058.010.0119. S2CID86068392.
↑ Rusina, L. Yu.; Orlova, E. S. (2011). "The relationship between phenotypic variability in future foundresses of Polistes Nimpha (Christ) (Hymenoptera, Vespidae, Polistinae) and infestation of their larvae by the mite Sphexicozela Connivens Mahunka (Acari, Astigmata, Winterschmidtiidae)". Entomological Review. 91 (6): 685–691. doi:10.1134/S0013873811060017. S2CID1999452.
Hornets are the largest of the eusocial wasps, and are similar in appearance to their close relatives yellowjackets. Some species can reach up to 5.5 cm (2.2 in) in length. They are distinguished from other vespine wasps by the relatively large top margin of the head. Worldwide, 22 species of Vespa are recognized. Most species only occur in the tropics of Asia, though the European hornet is widely distributed throughout Europe, Russia, North America, and north-eastern Asia. Wasps native to North America in the genus Dolichovespula are commonly referred to as hornets, but all of them are actually yellowjackets.
The Vespidae are a large, diverse, cosmopolitan family of wasps, including nearly all the known eusocial wasps and many solitary wasps. Each social wasp colony includes a queen and a number of female workers with varying degrees of sterility relative to the queen. In temperate social species, colonies usually last only one year, dying at the onset of winter. New queens and males (drones) are produced towards the end of the summer, and after mating, the queens hibernate over winter in cracks or other sheltered locations. The nests of most species are constructed out of mud, but polistines and vespines use plant fibers, chewed to form a sort of paper. Many species are pollen vectors contributing to the pollination of several plants, being potential or even effective pollinators, while others are notable predators of pest insect species, and a few species are invasive pests.
Dolichovespula maculata is a species of wasp in the genus Dolichovespula and a member of the eusocial, cosmopolitan family Vespidae. It is known by many colloquial names, primarily bald-faced hornet, but also including bald-faced aerial yellowjacket, bald-faced wasp, bald hornet, white-faced hornet, blackjacket, white-tailed hornet, spruce wasp, and bull wasp. Technically a species of yellowjacket wasp, it is not one of the true hornets, which are in the genus Vespa. Colonies contain 400 to 700 workers, the largest recorded colony size in its genus, Dolichovespula. It builds a characteristic large hanging paper nest up to 58 cm (23 in) in length. Workers aggressively defend their nest by repeatedly stinging invaders.
Paper wasps are vespid wasps and typically refers to members of the vespid subfamily Polistinae, though it often colloquially includes members of the subfamilies Vespinae and Stenogastrinae, discussed elsewhere, which also make nests out of paper. Paper wasp nests are characterized by open combs with down pointing cells. Some types of paper wasps are also sometimes called umbrella wasps, due to the distinctive design of their nests.
The Asian giant hornet or northern giant hornet, including the color form referred to as the Japanese giant hornet, is the world's largest hornet. It is native to temperate and tropical East Asia, South Asia, Mainland Southeast Asia, and parts of the Russian Far East. It was also found in the Pacific Northwest of North America in late 2019 with a few more additional sightings in 2020, and nests found in 2021, prompting concern that it could become an invasive species. However, by the end of the season in November 2022, there were no confirmed sightings in North America at all, suggesting they may have been eradicated in that region.
The Oriental hornet is a social insect species of the family Vespidae. It can be found in Southwest Asia, Northeast Africa, the island of Madagascar, the Middle East, Central Asia, and parts of Southern Europe. Oriental hornets have also been found in a few isolated locations such as Mexico and Chile due to human introduction. The Oriental hornet lives in seasonal colonies consisting of caste system dominated by a queen. The hornet builds its nests underground and communicates using sound vibrations. The hornet has a yellow stripe on its cuticle (exoskeleton), which can absorb sunlight to generate a small electrical potential, and this might help supply energy for digging. The adult hornet eats nectar and fruits and scavenges for insects and animal proteins to feed to its young. Because they are scavengers, the hornets may also serve as a transmitter of disease following consumption of infected plants. The hornets are a primary pest to honey bees, attacking bee colonies to obtain honey and animal proteins. The sting of an Oriental hornet can be quite painful to humans and some humans are allergic to stings.
The median wasp is a species of social wasp of the family Vespidae found throughout Europe and Asia. It builds aerial paper nests often in shrubs or trees, and occasionally under the eaves of buildings. It is most common to see this wasp between May and October during its 3.3 month colony cycle. Behaviours of this wasp include nest defense, curling which is believed to function in brood incubation, and gastral vibration which is involved in larval feeding. The median wasp has a halplodiploid sex determination system that results in a high level of relatedness within the colony. This species is not usually aggressive but will sting if they feel their nest is threatened. Most foraging in the nest is done by the workers once the first ones reach adulthood. These workers forage for insects, nectar, and wood for nest construction in temperatures as low as 7 °C (45 °F). The median wasp is known to be occasionally affected by the fungus Cordyceps sphecocephala and the Cricket paralysis virus.
Vespula germanica, the European wasp, German wasp, or German yellowjacket, is a species of wasp found in much of the Northern Hemisphere, native to Europe, Northern Africa, and temperate Asia. It has spread and become well-established in many other places, including North America, South America, Australia, South Africa, and New Zealand. German wasps are part of the family Vespidae and are sometimes mistakenly referred to as paper wasps because they build grey paper nests, although strictly speaking, paper wasps are part of the subfamily Polistinae. In North America, they are also known as yellowjackets.
Vespula vulgaris, known as the Common wasp, is a species found in regions that include the United Kingdom, Ireland, Germany, India, China, New Zealand and Australia. It is sometimes known in English as the European wasp, but the same name is used for the species Vespula germanica or German wasp. In 2010, the ostensible Vespula vulgaris wasps in North America were found to be a different species, Vespula alascensis.
The Polistinae is a subfamily of eusocial wasps belonging to the family Vespidae. They are closely related to the wasps and true hornets of the subfamily Vespinae, containing four tribes. With about 1,100 species total, it is the second-most diverse subfamily within the Vespidae, and while most species are tropical or subtropical, they include some of the most frequently encountered large wasps in temperate regions.
The eastern yellow jacket or eastern yellowjacket is a wasp found in eastern North America. Although most of their nests are subterranean, they are often considered a pest due to their nesting in recreational areas and buildings. This yellow jacket is a social insect, living in colonies of hundreds to thousands of individuals. Along with their subfamily, Vespinae, this species demonstrates supportive parental care for offspring, separation of reproductive and sterile castes, and overlapping generations. They aggressively defend their hives from threats and are known to inflict painful stings.
Dolichovespula saxonica, also known as the Saxon wasp, is a common social wasp found in the Palearctic region, specifically in large parts of Europe and in northern and central Asia. Although originally from continental Europe, D. saxonica has since colonised Britain, mainly in the south and east, but has been recorded as far north as East Lothian, Scotland. Most of their nests are above ground in trees and bushes, but they can also be found in buildings. Due to the proliferation of nests in urban areas and near residential homes, D. saxonica can be a pest for people. As a result, many human interventions are in place to remove Saxon nests. D. saxonica has been found to use chemical signaling in a lot of behaviours, such as alarm calls, fertility cues, and chemical trails.
The tree wasp is a species of eusocial wasp in the family Vespidae, found in the temperate regions of Eurasia, particularly in western Europe. Despite being called the tree wasp, it builds both aerial and underground paper nests, and can be found in rural and urban habitats. D. sylvestris is a medium-sized wasp that has yellow and black stripes and a black dot in the center of its clypeus. It is most common to see this wasp between May and September during its 3.5 month colony cycle.
Dolichovespula adulterina is a species of parasitic social wasp found in the Palearctic region. D. adulterina feeds on a variety of foods, including insects, spiders, arthropods, meat, molluscs, fruit, nectar, and larval secretions. D. adulterina was formerly considered to be synonymous with D. arctica from the Holarctic region, but more recent research indicates that D. arctica is a separate species.
Vespula rufa, commonly known as the red wasp, is a social wasp species belonging to the genus Vespula. It is found in northern and central Europe, parts of Asia, and northern parts of North America. Vespula rufa is characterised by red-brown markings and body segmentation, with the appearance varying amongst the different roles of individuals in the species. These wasps build small nests in dry banks underground that are not far below the surface. The colony cycle begins in the fall. Vespula rufa feed on live insects. One interesting fact about Vespula rufa is that the queen policing occurs in the species, and that worker policing occurs at much lower rates than other species in the genus Vespula. There are predators and parasites of the species. The species goes through a series of events before leaving the nest.
Vespula squamosa, or the southern yellowjacket, is a social wasp. This species can be identified by its distinctive black and yellow patterning and orange queen. This species is typically found in eastern North America, and its territory extends as far south as Central America. Within these territories, they create enormous, multiple-comb nests. The colonies may be either annual or perennial depending on the climate, and in many perennial nests, polygyny takes place. In addition, this species uses pheromones both as a sexual attractant and an alarm signal. This species feeds on insects and animal carcasses; it does not produce honey. V. squamosa, a social insect, has developed a parasitic relationship with the species V. vidua and V. maculifrons. Due to their painful, venomous stings, the species is considered a pest.
Dolichovespula arenaria, also known as the common aerial yellowjacket, sandhills hornet, and common yellow hornet, is a species of wasp within the genus Dolichovespula widely distributed in the North American continent.
Ropalidia romandi, also known as the yellow brown paper wasp or the yellow paper wasp. is a species of paper wasp found in Northern and Eastern Australia. R. romandi is a swarm-founding wasp, and manages perennial nests. Its nests are known as 'paper bag nests' and have different architectural structures, depending on the substrates from which they are built. The specific name honors Gustave, baron de Romand, a prominent French political figure and amateur entomologist.
Protopolybia chartergoides, also known as Pseudochartergus chartergoides, is a species of wasp within the genus Protopolybia. It is a social wasp found in southern Central America and northern South America.
Vespula infernalis is an obligate parasitic wasp, parasitizing the nests of other species in the genus Vespula. Its common host species is V. acadica in North America. It is sometimes called the cuckoo yellowjacket wasp due to its inquiline lifestyle. They differ from other parasitic wasps in their intensely aggressive behaviour during invasion and occupation of the host colony. Several morphological adaptations such as bigger body parts and highly curved stingers are present in these wasps to aid their aggressive parasitic behaviour.
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