Hornets and paper wasps

Asked May 15, 2020, 8:11 AM EDT

Hello! Over the past years I've discouraged the paper wasps from building nests under the deck rails, inside the table umbrella and beneath the walk-under deck simply by knocking down their nests either in Nov. or when they first were building in early spring. Not to say they haven't succeeded in building them, and then in the late stages of the season found my proximity a threat, and well, you know the end of that story. Ouch. How can I deter them in the initial stages? I’ve used the fake hornet’s nests with varying degrees of success- some years they’ve seemed to help, yet other years they seem to ignore it. Last year- no paper wasp problem at all. I discovered why in late fall once the branches were bare- a giant hornet's nest in the red maple. It had disintegrated by spring. Last summer the hornets did not seem to be a bother when we were on the deck and many other pollinators visited the potted flowers, and the paper wasps were nowhere- what a treat! Can I hope for the hornets to build a nest again? What kind of hornet could this be that was not a bother to us? My Questions: How to effectively deter the paper wasps? Will the hornets build a nest again? Are the hornets (type?) typically non-bothersome to humans? Thank you! ~Cara

Hennepin County Minnesota

1 Response

Hi Cara, thanks for the question and your patience!

Repelling any pests can be tricky—as you’ve found, sometimes you find something that works, but it’s not guaranteed to continue working in the future as conditions and nature are always changing. So pest management is never really a one-time thing, but something you have to continually monitor and adapt with. Hopefully the paper wasps don’t come back this year (sounds like you’ve done a good job keeping up with them so far!), but around now is a good time to check under your deck for any small nests. If you find any, they should be removed before colonies have a chance to develop further and they become more aggressive as the season progresses. Be very careful in removing them (you can use a long-handle broom to knock them down when the wasps are away) or hire a professional if you’re allergic. Some people have had success spraying soap/water or vinegar/water solutions on the sites to get rid of them.

Deterring them is usually a matter of being able to remove or identify what attracts wasps to your yard in the first place. In the wintertime, queens like to find small crevices to hide-out in; this usually ends up being near where they choose to build their nests come spring. This aspect can be hard to manage with the underside of your deck, but at least, if there are any cracks in the structure, be sure to seal them up. The other aspect to try to manage is reducing food sources. Their diets are primarily focused on protein (like bugs or other insects) and sweets (fruit sugars and nectar). If you happen to keep your trash can underneath the deck, you could move it or just make sure it’s covered up tight. And make sure you remove other unwanted food/drinks/perfumes that could could attract and agitate the wasps.

As for the hornets (a type of wasp, actually!), it’s hard to predict whether they’ll rebuild their nest in the same place. Over the winter, all wasps die except for queens. Queens will choose where to build their nests each year, with old nests remaining vacant. If the conditions in your maple tree remain the same, the new queens may discover it and choose to build there again since the old nest disintegrated—much more convenient a location for you than the underside of your deck—but it’s not guaranteed. Hornets tend to build aerial nests in open trees, so sounds like your maple is a favorable location. But like other wasps, they do sting if you appear as a threat to the colony or hive. They’ll typically leave you alone if you leave them and their nests alone. Depending on the type of hornet and whether or not you’ll allergic, some hornet stings can be deadly so always proceed with caution when you’re near any type of nest.

For more information on managing wasps, check out this website:
https://extension.umn.edu/insects-infest-homes/wasps-and-bees

Good luck this year and hope you find something that works!