In recent days, the Medina Extension Office has received a high volume of calls regarding large wasps found in homes. These have all been identified as European Hornets (Vespa crabro). As one of Ohio's largest wasp species, it is not surprising that these beauties can cause alarm. Their size easily draws attention and concern, leading to a call. But FEAR NOT.
-Beneficial predator in the landscape!!!! Carnivores that eat many soft bodied insects and pests in the garden.
-Native to Europe
- Found in the U.S. in the 1800's
- Considered "Naturalized" to Eastern North America now
- Worker size approximately 1 inch
- Queen size approximately 1.5 inches
- Mahogany brown, yellow and black coloration
- The only true hornet in Ohio
- One of the few that will fly at night, often found at windows or outdoor lights
So what's with the sightings this week?
European hornets, like many wasps and bees, build a new nest annually. Fertile queens emerge from hibernation in spring, right about NOW, and begin seeking a secure site to build their nest. European hornets build a paper-based nest inside of a protected cavity such as a hollow tree. They prefer a high nest entry, usually about 6 feet or more, for additional protection from nest raiders.
Unfortunately, this criteria may bring hornets into conflict with humans because attics, garages, barns and wall voids also fit the bill for a protected cavity site. And so if you have found a large European hornet in your home or barn this spring, chances are it is a new queen who has found a gap along a window, door, or external vent in her search for a safe cavity to begin building those pulpy brood cells. The queen will lay eggs in the first few nest cells which will hatch into her first daughters. They will take over building the nest for the queen, and start collecting caterpillars and other soft bodied insects to feed their sister larva.
Fortunately, if you are catching one now, you may prevent a nest from becoming established in your domicile. You can catch and release or kill the unfortunate hornet to rid yourself of the immediate issue. To prevent other insects or critters entering in the future, it might be time for a perimeter inspection around your home. Check for any entry points that can be caulked or otherwise sealed. Keep in mind that soffit vents and other openings may be required to properly ventilate your home. But gaps AROUND those pipes, spigots, and necessary exhaust vents (don't seal up your dryer vent folks) can be sealed with steel wool, caulk, or other appropriate sealant to prevent these and other critters from getting indoors. Of course some structures like barns and sheds may be impractical to seal up. Later in the season, if you find a nest within a structure, it may be best to hire a professional for removal. But remember, at the end of each season with the first good freeze, all the workers and old queen will die, and only a few fertilized females will survive to be the queen and repeat the process next year.
The European Hornet has seen a resurgence of negative attention in recent years due to the confirmation of Asian Giant Hornet (Vespa mandarinia) nests in the state of Washington. The Asian hornet does not occur in the Eastern half of the US and as of this date, have only been found in Washington state and areas of British Columbia, Canada. Extension does want the public to keep an eye open and report any suspicious or new invasive species, such as the new Spotted Lanternfly (Lycorma delicatula). But when it comes to the European Hornet and the Asian Giant Hornet, there are some easy keys to telling them apart.
- European Hornets have a yellow face and a mahogany reddish-brown head and thorax.
- Asian Hornets have an entirely yellow-orange head and a black thorax.
- European hornet abdomens have black stripes with visible TEAR-DROP shapes in them.
- Asian Giant Hornet has solid black and orange bands.
Feel free to call your local Extension office for assistance in identifying insects or if you suspect a new invasive pest in your area. If you are concerned for an Asian Giant Hornet (Vespa mandarinia) you can also use the Ohio Department of Agriculture's website for reporting possible infestations.
University of Kentucky, European Hornets