yellowjackets

Q&A: How Can I Get Wasps Out of My Compost?

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Yellowjacket (Vespula sp.). Photo: M. Talabac

Q:  Wasps took up residence in my compost pile this year. I could avoid them for a while, but I’m hoping I can use the pile again next spring. How can I get them out of there?

A:  Ground-nesting yellowjackets are probably the culprit here, and the good news is that they will disappear on their own by winter. In our area, social wasps like hornets, yellowjackets, and paper wasps don’t reuse the same nest for more than one year. By late autumn or early winter, the old queen, workers, males, and any juveniles that did not have time to mature will all die. Only mated young queens survive, leaving the nest of their birth to disperse and overwinter in a sheltered spot by themselves. They seek out insulated spots like hollows under fallen logs and nooks in stone walls, go into the insect version of hibernation, and emerge in spring as it warms up, each flying off to find her own site to start a new nest. She does all the nest-building and larvae-feeding work by herself until the first generation of young matures, so she has a limited ability to defend it from disturbance.

Nest remnants left in the compost pile will be abandoned (or will at least contain dead wasps) during winter, when you can safely dig it out for removal or just leave it to compost with the rest of the pile contents. Wild animals can also tear apart abandoned wasp nests, looking for easy-access morsels to snack on, though this presumably happens more regularly with visible above-ground nests.

Preventing a new generation of wasps from choosing the same appealing nest site in a future year might be challenging unless you enclose the pile in insect mesh or something to discourage queen wasps from exploring it in spring. Regular turning of the pile – recommended to keep it well-oxygenated anyway – might disturb a new queen too much to allow her to successfully begin a new nest.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.

These Wasps Are Not Social Distancing!

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two yellowjackets
Yellowjackets. Photo: Arlette/Flickr

Wasps are some of the most highly disliked insects and are often all linked together with bees as being “bad”. When my co-workers and I led a group of elementary school children on a bee lesson, our very first question for the group was: how do you feel about bees? Give us a thumbs up, thumbs down, or tilt your thumb to the side if you aren’t sure.

Many times students gave us a thumbs down or to the side with a sad story about being stung or a family member being stung. After letting the children talk, we found that the majority of the time, people were being stung by wasps and not bees.

Social wasps are listed in the family of insects called Vespidae, which includes the yellowjackets, baldfaced hornets, and paper wasps. All of these are aggressive stinging insects that we see in our yard and garden. Social refers to their nesting habits. Several wasps live all together in one nest and will defend that nest, which is why people get stung if they get too close. Social wasps make their nests from paper, which they make by chewing on wood, newspaper, or cardboard.

Paper wasp nest. Photo: A. Bodkins
Paper wasp nest in a pipe. Photo: A. Bodkins

It is important to know that not all wasps are social wasps and they are not all aggressive. Some, like mud dauber wasps, are solitary wasps. They are not aggressive because they do not have a colony to defend. Cicada killer wasps are solitary wasps also. They are aggressive towards cicadas (their food of choice), but not people, unless the female wasps are deliberately provoked.

In the social wasp group, yellowjackets are scavengers and will search widely for food, which includes garbage and carrion. These are often the pesky critters that try to get into your food at picnics. They can nest in the ground and will get aggressive if disturbed.

Social wasps get a bad reputation because of their ability to repeatedly sting. Many people can have an allergic reaction to their venom.

It is worth noting, however, that wasps have a valuable role in the environment — they are predators and even help with pollination. According to the North Carolina State web article on social wasps, a colony of 200 yellowjackets can eat 5,000 caterpillars in just one season.

yellowjacket nest hole in the ground
Ground nest entrance of eastern yellowjackets. Photo: Mohammed El Damir, Bugwood.org

Even though social wasps are considered beneficial insects, you should not feel guilty if you have to remove a nest if it is located in an area that poses a threat to human well-being. Always be cautious when using pesticide products such as aerosol wasp and hornet sprays. These can get into your eyes or on a location that is not intended, such as on pollinator plants, vegetables, or on picnic tables or outdoor dining furniture. Consult and follow the label for correct and safe use. You also can flag or mark the nest entrance and talk to a pest control company about removing it.

All social wasps produce an annual colony that will be destroyed with the killing frosts of fall. So, if a nest is in an out-of-the way location, just leave it alone.

Before taking any action with wasps (or bees), identify the insects first. Check the Home & Garden Information Center website for information or submit your photos to Ask an Expert for identification.

For more information, check out these additional resources.

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland, edited by Christa Carignan, Coordinator, Home & Garden Information Center, University of Maryland Extension. See more posts by Ashley and Christa.