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. 

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: 

While PFK understands the urgency and need to do something about this issue, we do not recommend the mass setting of wasp traps. This is also the advice of MPI. 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. Finally, homemade traps may hinder MPI’s monitoring, as they can attract the hornets away from MPI traps. MPI is methodically setting traps and using genetic testing as a way of identifying hornets. Homemade traps are not standardised, which could potentially affect the data. Overseas, instead of trapping, people have been able to track hornets flying back to their nests. Removing nests is a much more effective method of eradication than wasp traps.

This is an ongoing issue, so keep up to date via the MPI website. 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.

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. We do not recommend making a wasp trap as they lead to significant by-catch, which could lead to the loss of native pollinators. One thing you can make 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. 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. MPI and PFK do not recommend making traps, instead you can contribute by looking for and reporting hornets or nests.  

If you still 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 reduces 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. 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.