Yellow-legged Hornets in Kaipātiki

As most of you may have seen, yellow-legged hornets (Vespa veluntina), have been found in Kaipātiki. While this is a concern, as Kaipātiki locals and amazing PFK volunteers, we can work together to find and report any sightings to MPI.

This blog post covers information on the yellow-legged hornets and frequently asked questions. If you want to help contribute to stopping the spread of the hornet, the best thing that our volunteers and Kaipātiki locals to do is keep being the amazing eyes and ears of Kaipātiki, particularly within our reserves. This means looking out for hornets and their nests, and reporting them to the Ministry of Primary Industries (MPI) if found. Early detection by citizen scientists is one of the key ways of tracking invasive pests, so our combined surveillance can really make a difference. 

Latest Updates

Click here for quick FAQ answers.

What do they look like? 

One key identifier is that they are bigger than other wasps and bees in New Zealand. They are mostly black, with thin yellow bands, and a thicker yellow band towards the end of their body. Lastly, their legs start black by their body, and are bright yellow at the ends. Visit the MPI website for more details on how to identify yellow-legged hornets.

Photo of yellow-legged hornet, with description of visual characteristics. (Image taken from MPI)

If you see a hornet, make sure to take a photo of it first before reporting it to MPI either through report.mpi.govt.nz/pest, or by phoning 0800 809 966. Also, if you see an individual hornet, it is likely that there could be a nest in the area, so be vigilant and look for a nest nearby. 

Yellow-legged hornets make two types of nests, primary and secondary. You are more likely to find a smaller primary nest at this time, however as we enter late summer and autumn secondary nests may be created. Primary nests can be found under the eaves of houses, garages and in places where you would typically find other wasp nests. There is a clear difference between yellow-legged hornet nests, which are smooth, and other wasp nests which have visible cells. 

Left: image of yellow-legged hornet nest showing a smooth covering (image by IVANVEITO). Right: European paper wasp showing an open, celled nest (image by Blackbox).

Image of yellow-legged hornet queen making a primary nest. (image taken from MPI)

Why are they a threat?: 

Yellow-legged hornets pose several threats if they establish in Aotearoa. The first is that they are predators that attack native bees and a wide range of insects. This has knock-on ecological impacts such as decreasing already threatened pollinator populations and therefore plant species. Our native species are particularly vulnerable to invasive social wasps because they have not evolved any defence mechanisms against them. Similarly, Western honeybees are also vulnerable, and yellow-legged hornets are known to take out whole honeybee colonies, putting our agricultural sector and honey industry at risk.  

Finally, yellow-legged hornets pose a risk to humans as they are very aggressive and will attack any threats to their nests. The hornets can sting multiple times and will often attack in groups if close to the hive. They can also spit venom. In France, where yellow-legged hornets have become established, hornet attacks have caused anaphylaxis, and in extreme cases, death. One yellow-legged hornet queen can produce 12,000–15,000 hornets in a season. And, in France were estimated to spread at a rate if 78 km per year, with a nest density of up 4.81 nests per square kilometre. 

Wasp traps: 

The main way you can contribute to yellow-legged hornet surveillance is through finding and reporting hornets and hornet nests. Wasp traps may increase the chances of you finding them but have high rates of bycatch. Another option is with a lure jar. Lure jars made from a cloth soaked in sugar water that attracts yellow-legged hornets but does not drown them, this also decreases the risk of other insects drowning. However, be careful because attracting hornets can put nearby people and pets at risk of stings.

Effectiveness of wasp traps:

Before you make a wasp trap, understand that homemade (and commercial) wasp traps are un-selective, therefore lead to by-kill of bees and other insects. Overseas, yellow-legged hornets represented only 1% of trapped insects in wasp traps. In Kaipātiki, our restoration work includes increasing our native pollinators, therefore indiscriminate wasp traps put them at risk.

Furthermore, capturing individual hornets has little impact on colonies, which can grow from a single queen, and can easily replace workers. Since it is summer, the chances of capturing a queen are less than during spring or autumn, therefore the utility of wasp traps is mainly for monitoring, rather than directly reducing wasp populations. MPI is methodically setting their own traps and using genetic testing as a way of identifying hornets, they will also be increasing the number of traps over time. Overseas, instead of kill-trapping, hornets are live-trapped and tracked as they fly back to their nests. This is the route that MPI is likely to take under the advice of overseas experts within their technical advisory group. Removing nests is a much more effective method of eradication than wasp traps.

Making a wasp trap:

Wasp traps can be made from recycled materials, particularly large plastic bottles which can be cut and re-stuck together to create a funnel for hornets to fly into. Alternatively, windows can be cut on the upper sides of the bottle as entry points. Attractants are poured into the base to attract wasps inside.

There are two ways of making traps that can decrease the amount of by-catch, these can be used in conjunction.

The first is by using an attractant that includes either vinegar or alcohol (beer/wine), or protein (meat soaked in water). This will still attract other insects but not bees. Protein may attract other types of wasps, so it is important to understand the visual differences between them before reporting. Protein is also the main attractant to be used in the summer when workers increase.

And the second method is by placing a piece of gauze or material above the attractant as a physical barrier to stop caught insects from drowning. Caught insects can then be released. Though insects maybe annoying to some, they are still a vital part of the ecosystem, so making sure they are released is important.

The suggested attractant mixture from MPI is "400g of sugar, 10g of yeast, and 1 litre of water. You can also add 100ml of beer to this mixture." For the instructions of how to make a wasp tra form MPI, see here.

Hang traps in sheltered areas to reduce the amount of rain that may enter it.

For more information on no-kill traps here is information from the National Bee Unit of the United Kingdom. Please note: the information on the European Hornet, hotline and reporting links do not apply to New Zealand, if reporting a yellow-legged hornet please report via the MPI links provided in this blog post.

This is an ongoing issue, so keep up to date via the MPI website and social media. We will also keep this blog post updated. Let's work together to be the eyes and ears of Kaipātiki and help MPI eradicate the hornets before they spread.

Yellow-legged Hornet Nest (image not from New Zealand). Credit: Photo 410734176 by koekoe on iNaturalist, image cropped. CC-BY-NC.

Latest Updates:

25th November:

22 confirmed yellow-legged hornet queens have been found, still within the Glenfield and Birkdale areas with 14 showing signs of building nests.

20th November:

15 queen hornets have been found, still within the Glenfield and Birkdale areas with signs of nest building and two workers. The trapping area has extended and number of ground staff increased.

Edits have been made to our section on wasp traps to include how to make them. With the increasing numbers of nests found, and the shift to summer, the chances of catching hornets in traps have increased. Though there is still a high rate of bycatch, there are ways to minimise it, which we have included in our instructions.

14th November: 

The latest MPI media release reports that they have set up 180 traps to date. This includes those with protein baits. No hornets have been found in traps, re-enforcing the need for public surveillance. Watch this space for our #hornethunt campaign, encouraging those in Kaipātiki and beyond to methodically search their gardens, schools and parks for yellow-legged hornets.

13th November:

The MPI web-page link as has been changed to the new dedicated yellow-legged hornet response page.

12th November: 

One more queen and nest has been found in Glenfield and destroyed by MPI. MPI has increased the number of traps to 142 and are doing on the ground searches of common nesting areas (trees, eves of buildings, fence-lines etc.). There have been additional reliable sightings of hornets, but also some reposting of old images. MPI asks those outside of Kaipātiki to also be vigilant of hornets that may have spread further.

The best way to stop hornets continues to be destroying nests. If you live in the Glenfield area, you may want to do a thorough survey of your property, looking for hornets or hornet nests.

8th November:

Edits have been made to this blog post to align with the latest MPI notice in which they do not discourage the use of homemade hornet traps. PFK still does not recommend making homemade traps due to the significant by-catch of other insects.

FAQ: 

What do I do if I find one? 

If you find a hornet or nest the first thing you should do is take a clear photo of it. After getting a photo you can either report it at report.mpi.govt.nz/pest or phone 0800 809 966. If you have found a nest, it is best to call the hotline. 

I’ve found a wasp, how do I know that it is a yellow-legged hornet? 

If you’ve found something that looks like a hornet, take a clear photo and use your zoom to study the insect. Use the MPI identification descriptions to help you identify it. You can also upload it to iNaturalist, which will provide suggestions of the species. If you are in Kaipātiki, it is best to report any suspicious wasps online, even if you are not sure if it is a yellow-legged hornet.

Where are yellow-legged hornets found?

Individual yellow-legged hornets will likely be found foraging in gardens, and parks. Hornet nests will be found in similar places to other invasive wasps nests, such as the eves of houses or garages, but look different. Yellow-legged hornet nests are smooth and do not have visible cells (unless in the process of being built).

Where are yellow-legged hornets found in Auckland? 

The latest hornet sightings have been in Kaipātiki (Glenfield and Birkdale) but have also previously been found in Grafton and Albany. It is likely that they will spread to other parts of Auckland if not eradicated, therefore people in other areas of Tāmaki Makaurau should also be vigilant. 

Why are they a threat?

Hornets are highly aggressive and invasive predators that eat other insects such as native bees and honeybees. They put our native biodiversity and agricultural industries at risk, particularly honey production. They also can cause harm to human health.  

Are hornets dangerous?  

Hornets will not attack humans unless they feel threatened, but it is best to always be cautious. Stay at least 5 meters away from hornet nests. Stings from yellow-legged hornets are similar to other wasp stings, but may hurt more due to their larger size. Stings can cause anaphylaxis and the hornets also spit venom.

Should I make a hornet/wasp trap?  

MPI already have monitoring traps set up in Kaipātiki. Wasp traps lead to significant by-catch, which could lead to the loss of important native pollinators. If you want to make a wasp trap, see our wasp trap section. An alternative to a wasp trap is a lure jar to help attract yellow-legged hornets to report to MPI. Lure jars made from a cloth soaked in sugar water that attracts yellow-legged hornets but does not drown them, this also decreases the risk of other insects drowning. However, be careful because attracting hornets can put nearby people and pets at risk of stings. 

What is MPI doing about the hornets?  

Currently, MPI is in the monitoring and eradication stage. They have set up monitoring traps in the areas of interest and are destroying hornet nests when they are found.  

What will happen if we don’t stop them?  

If we don’t stop them now, the hornet population is likely to grow, spread and establish in the country. The response to hornets will also change if the population grows, from eradication to containment, then long-term management. Long-term management will add to the already high financial cost of managing invasive wasps, along with a big impact on our native biodiversity.  

I still really want to make a wasp trap, how do I stop by-catch?

There is no way to completely stop by-catch. The key way of contributing to the effort of stopping the yellow-legged hornet is still by looking for and reporting hornets or nests.  

If you want to make a trap, there are some ways to reduce the capturing of bees, but these are not foolproof and still catch other insects.

Using beer as a bait can reduce the attraction of bees due to the alcohol content. Additionally, protein, instead of sugar, can be used as bait, particularly in the summer, which can be created by putting raw meat or fish into water. This will be less attractive to bees.

As per MPI's latest notice (7th November, Facebook):

"A homemade solution of 400g sugar, 10g yeast, 1L water is a simple formula that may be attractive to the hornet, and local introduced Vespula wasps. You can also add 100ml beer to this mixture."

Finally, placing a gauze inside the trap, above the attractant, can stop non-target species from drowning and be released. However, this also means that the hornets will also not drown. Whether or not a gauze is used, caution is needed when emptying traps, as trapped wasps may still be alive. You may want to freeze the whole trap to kill the hornets. Keep caught specimens as they may be useful for MPI.