The loud, buzzing presence of cicadas signals a dramatic shift in the natural world. These insects, known for their distinctive, shrill song and the empty shells they leave behind, often appear in massive numbers. The visible aftermath of their emergence prompts a common question: do cicadas create holes in the ground?
The Purpose of the Holes: Emergence Tunnels
Cicadas do create holes in the soil, and these openings are exit tunnels constructed when the insects are ready to complete their life cycle. These tunnels are not built for feeding or casual movement but serve as the final, vertical pathway to the surface. The mature nymphs dig straight up from their subterranean homes, often just days or hours before they emerge as adults.
The timing of this final ascent is highly dependent on ground temperature. Nymphs wait until the soil reaches approximately 64 degrees Fahrenheit at a depth of about eight inches before initiating their emergence. This temperature threshold signals the right conditions for their transformation and subsequent breeding. Once the soil warms sufficiently, the nymphs begin their synchronized tunneling effort. This coordinated effort results in the sudden appearance of numerous small holes across the affected area.
Identifying Cicada Chimneys and Exit Holes
The holes you observe are the remnants of these emergence tunnels, and they generally appear in one of two distinct forms. The most common is a simple, round exit hole in the soil surface, typically about the diameter of a pencil or a dime. This open hole is the final aperture through which the insect crawls out.
In some areas, particularly where the ground is wet or heavily saturated, the nymphs construct a more complex structure called a cicada chimney or turret. These chimneys are small, hollow cylinders of mud and soil built up directly above the exit hole, often standing an inch or two above the ground. The nymph creates this miniature structure by pushing wet soil out of the tunnel and packing it around the opening, resulting in a small, dome-shaped mound. This construction helps to keep the tunnel from collapsing or filling with mud and water.
These chimneys are a telltale sign that a mass emergence is imminent, often appearing a few weeks before the insects actually surface. They represent a temporary engineering solution to a wet environment. This ensures the insect’s successful transition from an underground dwelling to the world above.
The Nymph Stage and Burrowing Behavior
The creation of the final emergence tunnel is the last act of the cicada’s long subterranean existence as a nymph. Cicadas spend the vast majority of their life cycle underground, which can last anywhere from two to five years for annual species, or 13 or 17 years for periodical species. During this time, they are wingless and use specialized, strong front legs for digging and moving through the soil.
The nymphs live in relative solitude, excavating small chambers near tree roots. They use specialized mouthparts to tap into the xylem, the water-conducting tissue of the roots, to feed on sap. This slow consumption of nutrients sustains the insect as it grows and develops through multiple juvenile stages.
Throughout their time below the surface, the nymphs are actively burrowing and moving to find new root systems and better feeding locations. The final, straight-up emergence tunnel is the last burrowing effort, contrasting with their meandering movements over the years. Once the nymph has reached its maximum size and the environmental cues are right, it will make this final, singular ascent to molt into its adult, winged form.
Impact on Yards and Gardens
Homeowners often express concern that the sudden appearance of hundreds or thousands of emergence holes will cause lasting damage to their lawns. The holes themselves are superficial and pose no real threat to the health of the grass. The small openings usually fill in naturally within a few weeks as the weather and normal yard activity take their course.
The mass tunneling action can have a beneficial, albeit temporary, effect on the lawn. The holes act as a form of natural aeration, which helps to break up compacted soil and promote better water and air circulation for the grass roots.
The only potential for harm to plants from cicadas comes from the adult females laying eggs. They create small slits in the bark of young tree branches to deposit their eggs, which can cause the branch tips to wilt and die back. This damage is a consequence of the reproductive cycle and is entirely separate from the harmless emergence holes in the turf.