Spring monitoring for yellow-legged Asian hornets

In spring, as temperatures rise, Asian hornet queens (Vespa velutina nigrithorax) emerge from hibernation.

Monitoring now may identify any queens which have overwintered in the UK.

Lynne Ingram, MB and Somerset BKA’s AHAT coordinator, recommends the use of monitoring stations rather than killing traps.

She says: “This allows us to get the evidence of Asian hornets that we need, without killing our native beneficial insects, in particular European hornets.”

At this time of year Asian hornet queens will be searching for sugary foods to build up their energy rather than preying on honey bees. So, all monitoring stations should be positioned where you can easily see them and check them daily - eg outside the kitchen window, or in a sunny spot in your garden. All beneficial insects should be released from monitoring stations daily.

From mid-May Asian hornet queens will be mainly in their nests and so monitoring stations can be removed.

We suggest the adaptation of Thorne’s traps to include wick stations inside to allow wasps and small flies to escape. 

Liquid bait – either a proprietary brand such as Trappit (sold as a wasp attractant) or a French recipe such as:

  • Dark beer mixed with 25ml strawberry dessert sauce and 25ml orange liqueur
  • 350ml sweet white wine (or white wine sweetened with sugar) + 20-30ml mint syrup

Please also observe your flowers where Asian hornet queens may be feeding. Any tree that oozes sap are also very attractive in spring.

If you think you have seen an Asian Hornet

  • Take a photo (or sample)
  • If you are suspicious and you have evidence, report a sighting on the Asian Hornet Watch App or on alertnonnative@ceh.ac.uk and to your local AHAT.

Adapting a monitoring station
Jersey is using a modification to the origin design to allow beneficial insects to escape. The wick pot prevents all but the smallest insects from entering from the side. They still require daily monitoring.

The trap:

  • Drill three 6mm holes in the flutings around the top of the Thorne’s trap.
  • The wick station

The wick stations in these pictures are cutdown sample pots, originally 7cm high and just under 5cm diameter. You can use other similar size small pots.

Cut the sample pot to half its height ie 3.5cm and fit the lower section through the top section base first. Place a small block of wood or similar over the top of the pot and tap the two parts together. That way you retain the screw top and the modified pot fits snuggly into the trap.

Drill a 12mm hole in the lid to take the wick which is made from paper towelling/Jeyes cloth etc. Fill with your liquid bait.

The wick pot prevents all but the smallest insects from getting down the side, and the liquid bait doesn’t evaporate so quickly. The holes in the trap allow beneficial insects to escape. Please monitor regularly.

With thanks to Somerset BKA and BeeBase.

April 2021

Tracking

Asian hornet trap

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