In late April and early May, European hornet queens are waking up from their overwintering and are in flight looking for places to build their nests. These large wasps prefer to use hollows inside of trees but have also been observed to use cavities in soil and wall voids in human-made structures. Usually, they pass without notice but ever since the discovery of Asian giant hornet (aka the murder hornet) in the Pacific northwest, European hornets have been commonly misidentified as this other more infamous non-native wasp.
How to tell them apart
Worker hornets in both species are quite large, European hornets are about an inch long while the Asian giant hornet is around 1.25 inches long. The emerging European hornet queens are almost 1.5 inches long, which contributes to their misidentification. The two species also have similar abdominal coloration.
Luckily there are some key differences you can easily see, even if you haven’t killed the hornet in question. It boils down to coloration on the thorax and head. European hornets in the US usually have a distinct dark red coloration to much of the thorax (the middle section) and most of their head. The dark red on the head usually covers the top and sides of the head, while the lower front of the head is yellow. Asian giant hornets on the other hand have a mostly uniform yellow-orange color to their head, thorax, and abdomen. There are dark brown stripes on the abdomen and the head has brown antennae.
So, if you see red on the front of the insect, it is most likely a European not an Asian hornet.
Should I be Concerned?
This species is non-native, like the Asian giant hornet, but has been in the US and Kentucky for over 150 years at this point. They are a stinging pest, particularly when their nest is threatened. Worker hornets will vigorously defend the colony and each individual hornet can sting multiple times. They can be commonly encountered in the woods, but they are attracted to perimeter lights at night and sometimes queens may construct their nest in an attic or wall void. Turning off outside lights can result in less attraction to your property and pest proofing as we have previously described can keep them from attics and wall voids.
If you end up with a hornet infestation in your home or outbuildings, it is best to work with a pest control professional to deal with the nest. If you absolutely must manage it on your own, you need to use an aerosol wasp and hornet product and ensure that you can spray it into the entrance of the nest. Soaking the outside of the nest won’t work and you should not breach the exterior of the nest to make a treatment hole. This will result in hornet-filled chaos. You should use the aerosol product at night, you should wear long sleeves tucked into gloves (preferably leather or other tough material) and long pants tucked into socks, you should have an escape route to a safe place in mind as well. Treating at night minimizes the chances of attack, and the aerosol products work quickly, but it is always better to be safe rather than stung.
If you have seen and killed a queen hornet, you have cut the problem off at its source! Keep an eye out for others and make a note of where they were inspecting to see if you need to do some pest proofing in that spot. We appreciate that everyone is on the lookout for Asian giant hornets. It is unlikely that we will find one in Kentucky any time soon, but it is good to know that people are monitoring for a potentially invasive species. If you want someone to double check on what you caught, you can always submit a photo sample to our Facebook page, Kentucky Bugs.
Jonathan L. Larson, Entomology Extension Specialist