Hornets and Wasps: how to get rid of them?

Asked December 31, 2019, 2:04 PM EST

Insect identification's not a strong suit. I think I have hornets and wasps. If possible, I'd like to get rid of them before the spring. 1) Hornets in my front yard. I've tried insect sprays. I tried drowning them by running a hose into the hole and letting the water run for several hours. Neither method worked. 2) Wasps. These showed up last summer. I haven't seen them since the weather's gotten a little colder. They seem to have driven out the carpenter bees. Also they seem less aggressive than the carpenter bees. Good. But they also chew on wood or more like nibble on it. Worse, I think they've made a nest in the crawlspace beneath my kitchen. Bad How can I get rid of these unwelcome insects? Thank you for your help. Cate

Anne Arundel County Maryland

1 Response

Many social wasps will not re-use a nesting site from year to year; the workers die off in winter, and the overwintering queen(s) disperse and seek refuge elsewhere by themselves until they're ready to start up a new colony in spring. This means that it is quite unlikely your problem sites from last year will continue to be so next year. That said, something in the habitat may have been attractive to a queen last spring, so evaluating the yard and building may help determine what areas could be altered to discourage new nest-building. We cannot identify the specific species of wasps from the photos, though if they were chewing on wood, they could very well be using the pulp to make the "paper" used in nest-building.

Being in one of our coastal plain counties, your soil may have been too sandy to allow the water to flood the nest cavity, draining as fast as it was trickled in. It's possible the wasp sprays (if that's the insect spray you tried) were only partially effective if younger generations of wasp workers matured and emerged after the effective period of the insecticide. There are overlapping generations of worker wasps in a nest, and the queen keeps producing them throughout the summer. If she survived, it's possible enough of her young survived and kept the nest viable. Environmental factors - such as rain and sun exposure - may also have degraded the pesticide residue before it could have more of an effect. You may need to contact a licensed pest control company to evaluate the presumed nest sites and/or make recommendations to discourage new nesting in spring. They could also make treatments for you, but only after a new nest is formed and located. Recommendations may include exclusion tactics for the crawlspace or over-seeding lawn if wasps were attracted to patches of bare ground that were easier to excavate. (Though in the photograph that doesn't appear to be the case.)

Despite being a nuisance (and safety threat if you disturb the nest) they are at least considered beneficial garden predators, as they hunt for common garden pests to feed their young.