Cicada killer holes are round burrows about the diameter of a quarter, dug into bare or sandy soil by large solitary wasps. They’re most noticeable in July and August, when female cicada killers excavate nesting tunnels in lawns, garden beds, patios, and along sidewalks. The holes often appear suddenly, sometimes dozens in the same area, with small mounds of loose soil piled next to each entrance.
What the Holes Look Like
Each burrow entrance is roughly half an inch to an inch wide, perfectly round, and usually surrounded by a U-shaped mound of excavated dirt. The tunnel behind it can extend 6 to 10 inches deep before branching into side chambers. A single female may dig several of these tunnels over her lifetime, and because cicada killers tend to nest in the same general area year after year, you can end up with dozens of holes clustered in one patch of yard.
The soil piles are what most people notice first. They look like small anthills but with a much larger opening. In sandy or loamy soil, the mounds can spread several inches wide. On slopes, the loose dirt often washes downhill after rain, leaving the holes more exposed.
Why They Choose Your Yard
Female cicada killers are picky about where they dig. They strongly prefer dry, well-drained soil with sparse vegetation or bare patches. South-facing slopes, sandy flower beds, the edges of patios, and thin spots in lawns are prime real estate. If your yard has compacted clay soil with thick grass coverage, you’re far less likely to see them.
The wasps return to favorable sites because the conditions that attracted the first generation persist. Daughters that emerge the following summer often nest in the same area their mother chose, which is why infestations can grow over several years if the soil conditions stay the same.
When the Holes Appear
Adult cicada killers generally emerge by the first week of July and remain active throughout the summer. Adults live approximately 60 to 75 days, spending most of that time hunting cicadas and provisioning their underground nests. Each side chamber in the burrow gets stocked with one to three paralyzed cicadas and a single egg. The larva hatches, feeds on the cicadas, then spins a silken cocoon in the fall and overwinters underground. It pupates and emerges as an adult the following summer.
By mid-September in most of the eastern United States, the adults are dead and the holes go quiet. The burrows remain in the soil through winter, though rain and frost often collapse the entrances. New holes appear the next July when the next generation digs fresh tunnels.
Are They Dangerous?
Despite their intimidating size (females can be nearly two inches long), cicada killers are not aggressive toward people. Males are territorial and will hover or buzz near anyone who walks through their area, but males cannot sting. Females can sting but rarely do unless grabbed or stepped on. The sting is mild compared to a yellowjacket or honeybee.
The real concern with cicada killer holes is cosmetic and structural. A heavily infested lawn can develop soft, uneven patches where the tunnels undermine the turf. Along retaining walls, pavers, or sidewalks, extensive burrowing can shift soil enough to cause minor settling. For most homeowners, the damage is limited to unsightly bare spots and dirt mounds.
How to Get Rid of Active Burrows
If you want to eliminate active holes, treat them in the evening when the wasps are inside and less active. An insecticidal dust labeled for ground-nesting wasps, applied directly into each burrow entrance, is the most effective approach. The returning wasp picks up the dust on her body as she enters and exits, which eliminates her within a day or two. Wear long sleeves and pants as a precaution, though the risk of being stung during treatment is low.
Pouring boiling water into burrow entrances is a chemical-free alternative. It disrupts the nest and can kill larvae in the chambers below. This method requires care to avoid burns and works best when the tunnel is relatively shallow. You may need to repeat it if the wasp re-excavates.
For a small number of holes, simply filling each entrance with soil every evening can discourage the wasp from continuing to use that tunnel. She may dig a new one nearby, but persistent filling combined with other deterrents can push her to relocate.
Preventing New Holes Next Year
Because cicada killers select dry, bare soil, the most effective long-term prevention is eliminating those conditions. Keeping vulnerable areas consistently moist through regular watering makes the soil unappealing for burrowing. Females strongly avoid wet ground, and drenching an area with water may cause them to abandon the site entirely.
Thickening your turf is equally important. Applications of lime and fertilizer encourage grass growth and can eliminate an infestation over time, since females typically look for bare soil surfaces to dig in. Overseeding thin patches in early fall gives the grass time to fill in before the next nesting season starts in July. In garden beds or areas where grass won’t grow, a layer of mulch or landscape fabric over the soil removes the exposed dirt they need.
Ground cover plants work well on slopes or ornamental areas. Anything that blocks direct access to loose, dry soil forces the wasps to look elsewhere. If you’ve had cicada killers for multiple years, combining irrigation changes with turf improvement is the most reliable way to break the cycle. One season of dense, well-watered grass is often enough to redirect the population to a different location.