Asian Hornet

[Germain]

It's not just the predation of honey bees that is the issue - they will hawk the hives that cause the bees to become stressed and they divert to trying to protect the hive which can lead to colony collapse due to starvation, bacterial or viral infection etc. The AH isn't fussy about the protein source for the larvae - any winged insect will do - bees are easy prey due to hives acting like an all you can eat buffet but I have seen them on dead fish, around Cancale, in France they can be found on the discard oyster shells, they have been spotted here (Jersey) on road kill. Adults require nectar as a food, energy source so in Spring when the queens emerge from hibernation they can quite often be found around Camellia bushes

[Charles B]

It's not just the predation of honey bees that is the issue - they will hawk the hives that cause the bees to become stressed and they divert to trying to protect the hive which can lead to colony collapse due to starvation, bacterial or viral infection etc.

Thanks for the detailed info Germain!
Do these pests have any natural ememies to keep them in check? What is being done to stop them?



Here is additional info from the German Government's 'Bundesumweltamt':
(English translation GPT-5 mini)

Who should take action?
Control requires experience and specialized equipment (personal protective equipment, aerial lift, etc.) and should therefore only be carried out by persons with a certificate of competence and the necessary equipment. There is also a danger to one’s own health, because secondary nests may be built at heights of fifteen meters or more and can be inhabited by several thousand insects that often defend the nest aggressively.

Nests should not be removed on one’s own for another reason: they may be nests of the protected European hornet (Vespa crabro). Native hornets must not be controlled. So that the responsible authorities can take the correct measures, the specific hornet species must first be identified by an expert.



This about 'secondary nests' is scary indeed!

[Germain]

It's not just the predation of honey bees that is the issue - they will hawk the hives that cause the bees to become stressed and they divert to trying to protect the hive which can lead to colony collapse due to starvation, bacterial or viral infection etc.

Thanks for the detailed info Germain!
Do these pests have any natural ememies to keep them in check? What is being done to stop them?



Here is additional info from the German Government's 'Bundesumweltamt':
(English translation GPT-5 mini)

Who should take action?
Control requires experience and specialized equipment (personal protective equipment, aerial lift, etc.) and should therefore only be carried out by persons with a certificate of competence and the necessary equipment. There is also a danger to one’s own health, because secondary nests may be built at heights of fifteen meters or more and can be inhabited by several thousand insects that often defend the nest aggressively.

Nests should not be removed on one’s own for another reason: they may be nests of the protected European hornet (Vespa crabro). Native hornets must not be controlled. So that the responsible authorities can take the correct measures, the specific hornet species must first be identified by an expert.



This about 'secondary nests' is scary indeed!

No natural enemies in Europe as yet - this is the first year we have observed European taking Asian on the wing - we don't have bee eaters in Jersey so I don't know if they have developed a taste for them yet.
Damp winters help reduce numbers of over wintering queens
Primary (embryonic) nests - these are built by the fertilised queen in spring and are similar to early wasps nests - the queen will tend these early larvae
once they reach around 40 or so workers these will prospect out and start to construct the secondary nest.

Primary nests can be anywhere - wood stores, garages, bbq's, bird boxes, porches are some of the places they have been found

Secondary nests. When they first arrived on the Island in 2016 the available literature suggested that they were an arboreal nesting species. In September 2020 I was invited with a couple of other people to see if we could use tracking dogs to help speed up the process of tracking down nests especially in woodland at the same time there were other experiments going on - use of heat detecting cameras, drones, placement of coloured spots on the thorax, streamers and feathers. Citizen science at its best. Feathers and mark one eyeball are great in the urban environment - nano trackers are too expensive. My dog was showing potential at being able to scent track nests and knowledge was building all the time - flight speed is pretty standard, so marked individuals coming into a liquid attractant could be timed, flight is quite direct to the nest, and so using old fashioned triangulation techniques the search area can be narrowed down. Prey is dissected in flight and the hornet voids a short distance away from the nest so a scent midden it created for clever, sensitive noses and it looked like it might work.

Then the first low nests were found - a farmer edge cutting a wall caught a granite stone in a wall and disturb a nest below the 6 foot (2mtr) mark, 2 gardeners at a local tennis club tidying the hedge encountered a nest at about 6 foot, another nest was found in a rabbit burrow alongside a footpath,
in 2021 25% of nests were located in bramble thickets or walls or low hedges - this may be due to our weather and the hornet is adapting to cope with it, at this point I withdrew as I wasn't risking my best friend and my UK pal had to withdraw his dog after he nearly lost her to a bee attack - she got too close to a hive.

The citizen science still continues - nests are still being dissected as it tells how close to emergence the queens are. The latest nest dealt with had 200 emerged gynes (females with fat reserves and ) [Gynes are larger than workers and drones) 100 gynes in advanced pupal form and 100 larvae in enlarged domed cases that indicated they are also gynes. The workers weren't counted. So that single nest had the potential to release 400 queens, now multiply that by the number of viable active nests this year and thats an awful lot of hornets taking bees, moths, butterflies, caterpillars, common wasps - you name it they will take it to feed the larvae.
This is the most recent map PN - Primary nest SN- Secondary nest E - Embryonic nest Courtesy of J De Carteret and the Jersey Asian Hornet Group

[Charles B]

This is a really fascinating topic Germain! And I view Jersey as being just as cold wet and windy as here in Schleswig - Holstein. But Germany mainly has problems with them down south in the states of Reinland - Pfalz and in Baden - Württemberg. Luckily there has been only a view isolated cases in Hamburg.

I just put up two bird houses on my balcony and fear they may end up becoming the homes for wasps instead. I'll have to keep a good eye out on them between now and Halloween!