Are Cicada Killer Wasps Dangerous? What Long Island Homeowners Should Know

No, not to most people. Penn State Extension explains that because cicada killers are solitary and do not defend a nest containing a queen and brood, they are unlikely to sting and generally ignore humans. The male may dive bomb right in front of your face defending his territory, but he has no stinger and cannot sting. Ohio State's fact sheet says females may sting when handled roughly but are typically mild-mannered and fly away when disturbed.

The one real exception is a wasp sting allergy. A cicada killer sting is a wasp sting, and someone who carries an epinephrine injector for yellowjackets should treat these the same way. For everyone else, the risk is the bluff, not the sting.

Females can, males cannot. The female's sting is a tool for her job: Purdue Extension describes her locating a cicada in a tree, delivering a precise paralyzing sting, and dragging it to the burrow, where she lays an egg on it. She has no reason to use it on you unless you grab her, trap her in clothing, or pin her with a bare hand. If that happens, treat it like any wasp sting. Wash it, ice it, and watch for the signs of an allergic reaction you would watch for with any other sting.

Size and the hole. Penn State puts males at about 1.5 inches and females up to 2 inches, with a black abdomen banded in whitish yellow and an orange-red head, thorax, wings, and legs. Nothing else digging a hole in your lawn is that big. The burrow entrance is about 1.5 inches across, with a U-shaped mound of excavated soil beside it, and you will see one wasp per hole, not a stream.

A ground yellowjacket nest is the opposite. Cornell notes yellowjacket colonies can grow to 5,000 workers or more by the end of summer, and that wasps can sting repeatedly. The hole is clean with no dirt mound, the wasps are half-inch and pour in and out in a steady line, and they will defend it. Bald-faced hornets, which Cornell describes as large black and white yellowjackets, build gray paper nests in trees and on eaves, never in the ground. If you see a stream of small wasps at a hole with no mound, stop and read our wasp and hornet page instead.

Because your soil and sun suit them. Penn State lists their preference as loose, sandy, dry, or well-drained soil in an area with little vegetation and full sunlight, and Ohio State adds that females prefer to dig where vegetation is sparse. Long Island's sandy glacial soil is close to ideal, and a thin south-facing lawn, a bare strip along a driveway, the edge of a patio, or a sandbox is exactly what a female is looking for in July. Add mature oaks and maples full of annual cicadas within a short flight and you have a cicada killer property. Your neighbor's thick, irrigated, shaded lawn is not.

July and August, with stragglers into early September. Penn State says adults live only about two to three months, from July to September, and Purdue puts adult death by mid-September. Males emerge first and set up territories, females follow, and the digging and cicada hauling runs through August. The larvae feed on the stored cicadas, overwinter in the burrow as mature larvae, and emerge as adults the next July. That is why the same corner of the lawn produces wasps year after year: the next generation is already underground.

No. The spring ground bees are mining bees, which University of Maryland Extension describes as not aggressive, seldom stinging, and important pollinators, with flying activity lasting only 2 to 4 weeks. They are a quarter to half the size of a cicada killer, fuzzy, and their holes are about the width of a pencil. Maryland's advice is that control should be avoided if possible, and that heavy watering with a lawn sprinkler will discourage nesting. We tell people the same thing. Let them finish, and they are gone by Memorial Day.

Leave them alone if you can. Cornell's IPM program asks people not to kill these large but very low risk wasps, and they do keep cicada numbers down. Most lawns with a handful of burrows can simply wait them out and overseed in September.

Treat when the location or the trend makes the risk real: burrows in a sandbox, along a pool deck, beside a playset, or in a walkway kids use barefoot; a family member with a wasp sting allergy; burrows undermining pavers or a retaining wall; or a count that keeps growing. We have watched a lawn in Nassau go from a dozen burrows to sixty in three seasons because nobody fixed the bare ground. That is a lawn worth treating.

Confirm the wasp. First we make sure it is a cicada killer and not a ground yellowjacket colony, since the two are handled completely differently.

Map every burrow. Late afternoon in July is when the mounds and the traffic are easiest to see. We mark each one.

Treat each burrow directly. Penn State and Ohio State both point to a labeled insecticidal dust applied into the burrow opening in late evening or early morning, when the wasps are inactive and in their burrows. That is what we do, with a labeled product and the entrance left open so the female contacts the treatment.

Recheck at 24 to 72 hours. Activity drops sharply within a few days. Any burrow still active gets a second application.

Close and repair. Holes are closed, mounds raked, and bare spots topsoiled and seeded. September overseeding is the real prevention.

Written 6-month guarantee. Cicada killer treatment carries a 6-month written guarantee, and most lawns need one visit per season. Quotes are free and in writing before any work starts. If the phone call makes it clear you do not need a treatment, we will tell you that.

Take away the bare ground. Maryland Extension's list is the right one: thicken bare and thin spots by overseeding in the fall, cover bare soil with 2 to 3 inches of mulch or a thick groundcover, and run a sprinkler over the nesting area during the digging season. A dense, irrigated lawn is not where a female cicada killer wants to dig. Plugging a burrow with dirt does not kill the wasp; she opens a new entrance beside it. Fix the turf and the wasps go find a sandier yard.