Raised tunnels and dead grass patches in a lawn signal the presence of mole crickets, a destructive turfgrass pest prevalent across the southeastern United States. Adult mole crickets measure about one to two inches in length and possess distinctive shovel-like front legs evolved for burrowing. They cause damage in two ways: tunneling just beneath the soil surface, which severs grass roots, and direct feeding on those roots and young shoots. This activity leads to the formation of brown areas and turf that feels spongy underfoot.
Identifying the Pest and Optimal Timing
Effective management of mole crickets depends on treating them during the correct life stage. Mole crickets undergo an incomplete metamorphosis, progressing from egg to nymph to adult, with one generation developing each year. Eggs are laid in underground chambers in the spring, hatching in late spring or early summer, generally between May and July.
This period, when the crickets are small nymphs, represents the most vulnerable stage for control measures. As nymphs grow larger, they become more robust and difficult to eliminate. By late summer, the crickets are larger and cause the most visible damage, but control is significantly harder to achieve.
To confirm an infestation and identify the life stage, use the “soapy water flush” technique. Mix two fluid ounces of liquid dish soap into two gallons of water. Pour this mixture over a two-square-foot area where activity is suspected. If mole crickets are present, the soap will force them to surface within a few minutes, allowing for identification and population counting.
Non-Chemical Control Strategies
Biological and cultural methods offer a sustainable approach for managing mole cricket populations without synthetic pesticides. A beneficial control agent is the nematode, Steinernema scapterisci. This nematode actively seeks out and infects mole crickets, introducing bacteria that kill the host.
Unlike general-purpose nematodes, S. scapterisci is specialized to the pest mole crickets, reducing risk to other soil organisms. It is effective against adults but less so against nymphs, making it better for long-term population suppression. Nematodes must be applied to moist soil, ideally in the early morning or late evening to protect them from heat and ultraviolet light.
Cultural control methods focus on making the lawn less hospitable. Mole crickets are attracted to moist soil, as females prefer wet areas for egg-laying and nymphs thrive there. Reducing excessive irrigation, especially in naturally damp areas, discourages egg-laying and development.
Improving overall turf health through proper fertilization and aeration helps the grass recover quickly from minor damage and withstand tunneling. Physical methods, such as light traps, can capture adult crickets during nocturnal dispersal flights, but this serves primarily as a monitoring tool.
Targeted Chemical Applications
When an infestation is severe and non-chemical methods are insufficient, synthetic insecticides offer definitive control. Timing remains paramount, with treatments aimed at the small, newly hatched nymphs in late spring or early summer providing the best results.
Chemical products are available in two main formats: granular and liquid. Granular insecticides are broadcast over the lawn and must be watered into the turf after application to move the active ingredient into the soil. Liquid spray formulations must also be watered in immediately following application to ensure penetration through the grass thatch.
Insecticidal baits represent a third, highly effective option, utilizing an attractive food source laced with an insecticide. Baits work only if consumed, so apply them in the late evening when pests are most active at the surface. Unlike granular and liquid insecticides, baits should not be watered in after application, as moisture dissolves the pellets and renders them ineffective; water the lawn the day before application instead.
Common active ingredients fall into several chemical classes, including neonicotinoids (like imidacloprid and clothianidin), pyrethroids (such as bifenthrin), and fipronil, which is known for providing extended residual control. To mitigate the risk of the crickets developing resistance, it is advisable to alternate between products containing different chemical classes for subsequent treatments.
Regardless of the product chosen, strictly following the label instructions is mandatory for safety and efficacy, particularly concerning watering requirements and safety precautions. Once the infestation is eliminated, damaged turf can be repaired through reseeding or sodding to restore the lawn’s appearance.