Vespa velutina – The Asian Editors:Thomas Mollet (ADAAQ) and Claudia de la Torre (CNDA) Translated by Pam Todd

This article first appeared in Bulletin Technique Apicole, 33(4), 2006, 203–208

THE ASIAN hornet Vespa . During the velutina nigrithoraxis is a period June to September, early studies show an predator of domestic intensity of hornet attack honey bees and other activity occurring during the social hymenopterans. Its whole of the day. spread in France has Beekeepers were justifiably resulted in a deep concern distressed to see their hives as well as the urgent repeatedly and regularly attacked by the Asian hornet need for research and and by the European hornet experimentationinthe during the month of June. world of beekeeping.

Observers studying the J Blot IMPACT ON behaviour of Vespa velutina The Asian hornet is spreading throughout France. It is of AGRICULTURE AND near hives described their concern to beekeepers as it predates on honey bees RISKS TO HONEY activity thus: the hornet hovers over the entrance to BEES ahiveatadistanceof that they are generally very temperature of the mass to weak, low in foragers or around 45 °C and the All are predators of 30–40 cm, then tries to queenless. Such colony hornet dies because of the honey bees but in varying catch foragers, primarily conditions have not been heat. degrees according to those returning to the hive reported, to our knowledge, species and availability of loaded down with nectar or The European honey bee under normal autumn food sources. pollen. The hornets charge Apis mellifera, which has conditions. at them from below and naturalised in Asia, has In Asia (Kashmir), as in force them to drop to the adopted the same defence China, Vespa velutina is DEFENCE BEHAVIOUR ground before paralysing strategy but less effectively. considered a fearsome them and carrying them OF HONEY BEE enemy of honey bees. Fewer workers join the ball away. According to COLONIES According to literature, it is of bees – one third fewer C Villemant, each hornet able to destroy up to 30% In Asia, has than the Asian species. The only consumes a portion of of a colony of the Asian developed an efficient less efficient behaviour of the prey herself. She honey bee Apis cerana. defence strategy. The bees Apis mellifera in Asia is decapitates it, removes the Hornet workers attack the pack themselves into a probably due to its more legs and wings, and makes honey bee guards one by compact mass around the recent introduction to the the body into pulp before one, before robbing their hornet, forcing the internal predator. taking the meal to the nest brood nest in order to feed and feeding it to the larvae. their own larvae. The attempts by hornets to It is difficult to ascertain whether these descriptions access beehives are refer to feral honey bee numerous and frequent, particularly at the end of the colonies or to managed Calendar colonies, nor is one told of season (September to For Sale the size or state of health of December) when the the colonies concerned. production of new queens makes high demands on In France, the predatory hornet workers. behaviour of Vespa velutina towards honey bees and Beekeepers who have Beekeeping Holidays other appears more visited their colonies after Wanted significant than that of the such an attack have found

Bee Craft September 2007 Page 11 The nest of an Asian segments edged with a thin Thenestgenerallyhasa hornet colony can be over 40 cm in diameter band of yellow. Only the single entrance, positioned fourth abdominal segment half-way up the height of has a wide band of thenestinthecaseofolder yellow–orange. colonies and below that for nests which have just been HABITAT AND started. The entrances are DESCRIPTION OF THE holes of 1.5 cm in diameter, NEST protected by an awning of JM Brandely papier-maché. In France few observations imported with Chinese According to current Nests grow progressively describe this defence merchandise from Yunnan. observations, Vespa velutina strategy and it appears that makes its nest primarily in from spring until autumn. At it only occurs in colonies of Spread of Vespa thebranchesoftreesbut maximum height, the nest black bees. In the majority velutina in France sometimes it will choose is usually made up of 6–7 of colonies grouping of bees well-ventilated man-made ‘cell cakes’ or strata, which By the end of 2006, the contain the brood nest. (up to 100) is seen at the shelters such as barns or Asian hornet was present Nests have been found with entrance to the hive, sheds. Very occasionally, throughout Aquitaine in the 14 such strata. Each stratum anticipating attack or nests are found suspended departments of has a diameter of attempted entry. When a from cracks in walls. Lot-et-Garonne, Gironde and 23–29 cm. The edges of the hornet threatens, several Literature tells us that they Dordogne. Several sightings strata are separated from bees charge in her may also choose an were subsequently made in the outer ‘envelope’ by a 15 direction, causing a under-floor cavity. momentary ‘backing off’. the departments of Landes, mm space. The distance Pyrénées- Atlantiques, Spotting nests is often between strata is 10–12 mm. AREA OF Tarn-et-Garonne, difficult as they can remain Each individual cell DISTRIBUTION Hautes-Pyrénées, hidden until the leaf fall in measures, on average, Haute-Garonne, Gers, Asian Origins autumn and winter reveals 8.5 mm in diameter, with a Charente, Charente-Maritime, their position. depth of 26–29 mm. Up to and Corrèze. The Asian hornet is normally Generally, the workers form 17,000 cells per nest have found in the area bordered Overall, the area of the nest in the shape of a been reported. by Northern India and distribution measures sphere, slightly taller than it Atthetimeofmaximum China, as well as the almost300kmfromnorth is wide, which often population density, an Indo-Chinese peninsula and to south and 200 km from exceeds 40 cm in diameter. estimated 500 hornets the Indonesian archipelago. west to east. Today the In Lot-et-Garonne, Dordogne inhabit a nest of 90 cm in Individual hornets of the species is well established and Gironde, an average height. This figure does not sub-species nigrithorax in France, most nest measures 60–90 cm in take account of foragers introduced into France are predominantly in the height and 40–70 cm in absent from the hive at the presumed to be of Chinese south-west. diameter. The nest has an time of counting. origin. The climatic exterior ‘envelope’ made up conditions of continental BIOLOGY OF THE of 5–6 layers of In the North of Thailand, Asia where they are SPECIES papier-maché, spaced by scientists have collected a normally found are similar gaps of 5–10 mm. The colony containing around The species Vespa velutina to those of Southern average thickness of each 1500 insects in a nest has around a dozen known Europe. layer is 45 mm. measuring 50 cm in sub-species. The Introduction into sub-species present in France France, Vespa velutina nigrithorax,iseasily The new species of distinguishable from the European fauna, Vespa European hornet, Vespa velutina nigrithorax,was crabro (the only other officially recognised as hornet living in France) by resident in France in 2005. its size and its colour. The It was reported for the first adult measures around time in Lot-et-Garonne. The 30 mm in length, its thorax The nest is made up of five suggestion is that the first is dark brown and its to six layers of specimens were accidentally abdomen has gastric papier-maché P Lieniard Page 12 Bee Craft September 2007 The huge size of the nest diameter and comprising deserted. Only one can be seen here. The inner more than 6000 cells. examined in Gironde structure of strata is visible LIFE CYCLE revealed two living queens. on the right Normally, to over-winter, Egg laying period young fertile queens hide Thestartandtheendofthe themselves in narrow egglayingperiodofVespa crevices (rotten tree trunks, velutina is difficult to mossy river banks, etc).

determine. The activity of During the winter of Anna Legrand the fertile females depends 2006/7, which was Charles Janet on a nest of At the end of the season on temperature. An early relatively warm and very Vespa crabro demonstrated they are particularly return of hot weather can damp, single over-wintering the development of hornet attracted to ripe fruit. stimulate early laying queens were found in the workers only. This he found activity but for there to be cavities left by the larvae of Their diet depends on what to be very variable the start of a colony, it is Cerambycide (long–horned is locally available, on the depending on exterior also necessary that the beetle) in an oak blown state of the colony’s temperature, lasting 55 days queen be adequately fed. It over by a storm, whereas development and on the therefore appears probable the hornet’s own nest was during the month of May, level of competition from that even though queens still occupied, at least until and 30 days during the other predators. may start laying some eggs December, by the colony’s month of August. Hornets, in common with in February, foundations of workers. The development of Vespa honey bees, have two basic nests may well be started velutina workers follows the dietary requirements: sugars later. Natural Enemies same pattern: 30 days in – for energy for the adults, Over-wintering ThenestsofVespa velutina summer but probably less and proteins – for the have natural predators in than 55 days during the nourishment of the brood. In sub-tropical Asia colonies Aquitaine. In the period of warm spring weather of the are not perennial. The few pre-winter decline of the period of observation. BEHAVIOUR AND workers left alive, along colony, green woodpeckers, RISK TO HUMANS with a little of the brood, jays and tits are often seen Queen Mating According to initial cannot maintain an pillaging nests and eating The individual flights of the observations of Vespa adequate temperature for the remaining larvae. It is fertile males and, later, the velutina in France, the Asian life to continue. In the not yet known if there are new generation virgin hornet is not generally annual life cycle of the other hornet predators. queens, take place at the hornet the colony is, to all aggressive towards humans. One queen per nest end of the summer. The They have shown no sign of extents and purposes. as males seek out the females dead as the individual aggressive behaviour, either per year in order to mate. inhabitants by the end of in flight or in response to the year. In the normally According to the literature, The sexual pheromones human activity or loud favourable climatic one queen creates only one produced by the virgin noises. colony per year. She dies at conditions in the area of queen appear to play a part Throughout spring and theyear’sendanditisher natural distribution the new in bringing together the summer, nocturnal descendants (fertile queens over-winter, sexes. behaviour is characterised females) who become sheltering alone or in small by a concentration of groups in small cavities. founders of colonies in The mating itself has only following years. In spring rarely been observed, several hornets on the In France it is thought that each queen roughly shapes except during conditions set exterior surface of the nest. the nest of Vespa velutina a new nest and develops a up by the observer. It is only when the first in winter will not contain a new colony which will frosts occur that these living colony. The hornet contain only one queen. DIET hornets will enter the nest queens that have itself during the night. successfully over-wintered Life span of workers The diet of Vespa velutina is leave their shelters in spring as yet undetermined. In The daily rhythm of the to found a nest elsewhere. We are led to believe that general hornets eat not only species is characterised by In Aquitaine, all the nests, thelifeexpectancyofthe bees but also crickets, their first flights taken at even the largest, observed Asian hornet is the same in butterflies, flies and other first light (or at sunrise from outside during the France as it is in Asia. A insects. They also eat during frosty periods). The month of February were study carried out in 1895 by spiders. intensity of the comings and

Bee Craft September 2007 Page 13 goings does not appear to after extraction. They vary throughout the day. will attract hornets. Protection strategies Control of the

To date, the extent of the u Search out and kill new invasion is such that all queens in the area of attempts to eradicate Vespa the hives, particularly in velutina seem ineffective. February and March. The control measures u Set up all-year-round oultined below are still in traps, particularly near The spread of the Asian the process of research and honey bee mating hornet through France will be the subject of further hives, to reduce the studies in 2007. level of predation (use to those who make their classic wasp trap Protection of hives living from all crops that equipment). need honey bee pollination. u Reduce entrances to u Destroy nests in order to That the hornet attacks 6 mm high. Traditional limit reproduction of the foragers and, more metal entrance strips species. This is precisely, the pollen ADAAQ is the Association will not stop entry. particularly important collectors, is a cause for de développement de before the annual concern, in that they are yet l'apiculture en Aquitaine. u It seems that tall grass migration of the new another threat to our honey CNDA is the Centre in front of the hives queens in autumn. Take bee colonies in the modern National de développement hinders hornet activity care to avoid personal world. apicole. when capturing flying danger or danger to Further research studies are OPIDA is the Office pour bees. others. already in place for 2007.u l'information et la u documentation en Refrain from leaving wet CONCLUSIONS frames in the open, Scientific and apiculture It appears that the whole Technical Editors world expects that we should aim to eradicate u Museum national Vespa velutina from France d’histoire naturelle in view of the speed of (MNHN): Claire expansion and the rapidly Villemont enlarging area of its u Institut national de la presence. Further, its recherche agronomique expansion into the rest of (INRA) d’Avignon, Southern Europe seems Laboratoire inevitable. But we are forgetting for the moment d’entomologie: Bernard the need to study and learn Vaissière more about the insect and u Centre National de la the consequences of its recherche scientifique presence, in order to assess (CNRS): Gérard Arnold correctly the degree of et Agnès Rortais danger from Vespa velutina u Service régional de la to beekeeping. protection des végétaux Currently professional (SRPV): Catherine beekeepers are not Marque-Perrau reporting the more extreme u Laboratoire national de la results of encounters protection des vegetaux between honey bee (LNPV): Jean-Claude populations and the hornet. Streito However, it may be that an increase in the effects of Thedebateastotheroleof this species becomes hornets continues. See economically worrying, not Letters (page 27) for Peter only to beekeepers but also Hutton's thoughts.

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