Mole crickets are pests that cause significant damage to turfgrass and gardens, primarily in the Southern United States. They use large, shovel-like forelegs to tunnel just below the surface, which dislodges plant roots and creates unsightly raised runways. Species like the tawny mole cricket also feed directly on grass roots and young shoots, leading to widespread plant death. Protecting a lawn or garden requires a systematic approach using effective, non-chemical, natural removal strategies.
Identifying and Assessing Mole Cricket Damage
Recognizing the early signs of mole cricket activity is the first step toward effective management. The most visible indication is the presence of raised, winding tunnels that look like miniature mole hills, which are typically found in the turf. These tunneling runs cause the ground to feel spongy when walked upon because the turf has become detached from the underlying roots. As the crickets feed and tunnel, affected areas eventually turn brown and die, often appearing as irregular patches of dead grass.
To confirm an infestation, the soap flush test can be performed. Mix approximately two tablespoons of liquid dish soap with one gallon of water. Pour this solution slowly over a two- to four-square-foot area of suspect turf, preferably in the early morning or late evening when the insects are closer to the surface. The soapy water irritates the crickets, forcing them to emerge from the soil within a few minutes.
The number of crickets that surface provides a reliable count of the local population density. If two to four mole crickets emerge from the tested area, the population is dense enough to warrant immediate control action. This assessment technique is important because it guides the selection of the most appropriate natural removal method.
Utilizing Biological Controls
Long-term, sustainable control of mole crickets often relies on introducing or encouraging natural predators, known as biological control agents. The use of beneficial nematodes, specifically Steinernema scapterisci, is one of the most effective and targeted methods. This entomopathogenic nematode is a specialist parasite that actively seeks out and infects mole crickets in the soil.
Once the nematode enters the mole cricket’s body through natural openings, it releases a symbiotic bacterium that multiplies rapidly, killing the host within a few days. The nematodes then reproduce inside the dead cricket, with their offspring eventually returning to the soil to continue the cycle. Optimal application timing is crucial for success, typically targeting the large nymphs and adults in the spring or fall when they are most abundant near the soil surface.
For the nematodes to be effective, the soil must be kept moist, and application should occur during overcast conditions or in the evening to protect the organisms from damaging ultraviolet light.
Another powerful biological control agent is the parasitic wasp, Larra bicolor, which was introduced to control invasive mole cricket species. The adult female wasp hunts for a mole cricket, temporarily paralyzes it with a sting, and then deposits a single egg on the paralyzed insect. The wasp larva hatches and feeds externally on the mole cricket, eventually killing it.
The effectiveness of Larra bicolor is enhanced by planting nectar sources, as the adult wasps require nectar for energy and survival. The shrubby false buttonweed (Spermacoce verticillata) attracts these wasps, encouraging them to remain in the area. Establishing these plants near infested areas helps maintain long-term suppression of the mole cricket population.
Cultural Practices and Physical Removal Techniques
Adjusting routine lawn maintenance practices can make the environment significantly less appealing to mole crickets. Since these insects prefer moist soil, reducing excessive or unnecessary irrigation can naturally limit their activity near the surface. Maintaining a dense, healthy turf with an appropriate mowing height also helps create a physical barrier that discourages tunneling and feeding.
Reducing the amount of thatch is also beneficial. Thatch is the layer of organic matter that accumulates between the soil surface and the grass blades. Excessive thatch provides an ideal, protected habitat for mole crickets, so periodic dethatching removes this cover. Minimizing outdoor lighting in infested areas can also reduce the number of new adults flying in, as mole crickets are attracted to bright lights at night.
Physical removal offers a hands-on approach for immediate, localized control. The soap flush solution used for identification can also be used as a direct removal technique by simply collecting the crickets as they surface. Another effective method involves creating simple pitfall traps by burying a smooth-walled container, such as a glass jar or plastic cup, flush with the soil surface.
The container can be partially filled with a mixture of water and molasses or beer, which acts as an attractant. Mole crickets foraging at night will fall into the trap and be unable to climb out. These traps should be checked and emptied daily for best results. In areas that can tolerate temporary standing water, controlled flooding of a lawn section for a day or two can also force mole crickets to the surface for manual removal.