Mole Crickets
Mole crickets are large, brownish insects. They are rather cricket-like in shape but their front legs are mole-like and used for digging. Adults have wings and many are powerful, though clumsy, fliers. The body is covered with short, dense hairs. Some species have darker or lighter markings on the thorax.
The two native Oklahoma species (Northern and prairie mole crickets) are found mostly in the eastern two-thirds of the state. These and other native species are found throughout the eastern United States. The southern and tawny mole crickets are found along the Gulf and Atlantic coasts. Along with the short-winged cricket, they were accidentally introduced into the U.S. from South America.
Historically, the prairie mole cricket was found in prairie areas in central and eastern Oklahoma, eastern Kansas, southwestern Missouri, and northwestern Arkansas and in small areas in Illinois and Mississippi. Recent Oklahoma records are from eight counties in the central and northeastern areas of the state. At one time, this species was being considered for threatened status under the Endangered Species Act, but it is not listed due to insufficient information about its distribution.
Northern Mole Cricket, Neocurtilla hexadactyla
The front tibia has four claws and the hind femur is longer than the pronotum. The front femur bears a short, nearly semi-circular process armed with stout setae (hairs). Length: 1 - 1 3/8 inches.
Prairie Mole Cricket, Gryllotalpa major
The front tibia has four claws and the hind femur is longer than the pronotum. The front femur bears a knife-shaped, curved, acute process. Length 1 1/2 - 1 3/4 inches.
Southern Mole Cricket, Scapteriscus acletus
The front tibia has two claws that are separated by a space that is almost as great as the width of the claw and is “U” shaped. The hind femur is shorter than the pronotum. There is no process on the front femur. Length: 1 - 1 1/4 inches. This species has been reported from either Cherokee, OK, or Cherokee County but is not known to be established here. It was introduced into the southeastern United States in the early 1900’s and now occurs along the coast from Texas to North Carolina. It might eventually reach southeastern Oklahoma and specimens from this area should be examined with this possibility in mind.
Tawny Mole Cricket, Scapteriscus vivinus
The front tibia has two claws that are separated by a space narrower than their width, and is “V” shaped. It was introduced into Brunswick, Georgia in approximately 1899 and is considered to be the most damaging mole cricket of turf in the southeastern U.S. This species has not been reported in Oklahoma.
Life Cycle
Mole crickets spend most of the year burrowing just below the surface of the soil. They are active above ground in spring (April and May in Oklahoma) for mating and dispersal flights and to some extent in fall (September and October). Eggs are laid in burrows in the soil in the early summer. Southern mole crickets mature in about one year while the northern and prairie species probably have a two- or three-year life cycle.
Hosts
Depending on the species, mole crickets eat plant roots, insects, or decaying organic matter.
Damage
The northern mole cricket prefers damp areas along the margins of streams, lakes, or ponds or in low areas in grasslands. They can damage well-watered lawns, golf courses, etc. by dislodging plants or seedlings as they burrow beneath the soil surface. Dislodged plants become dry and soon die. Mole cricket burrows may be very evident, especially in newly seeded or sprigged turf. Mounds of dirt are pushed above the turf and the damaged area is easily scalped.
The prairie mole cricket occurs in tall grass prairie and prefers drier areas. It does not survive plowing or heavy grazing and is now found mostly in hay meadows and other undisturbed areas. It does not cause economic damage in these areas.
Inspection & Control
Mole crickets in turf generally reveal their presence by surface tunneling, but tunnels of small immature crickets are inconspicuous and nearly formless. Once detected, mole crickets must be flushed from the soil if they are to be identified to species. Pyrethrins are the most effective flushing agents, but liquid dishwashing soaps (1 tablespoon per gallon of water) are cheap and available substitutes. The mixture is applied with a garden sprinkler can at a rate of about 1 quart per square foot and the treated area is watched for emerging crickets for several minutes. If crickets are in the area, they will normally come to the surface within 20 minutes.
Another method of collection is flotation. Select a large can such as a two-pound coffee can or one with a diameter of at least 6 inches, from which both ends are removed. Push the can into the turf, through the thatch, and into the soil surface in an area suspected of being infested. Then fill the cylinder with water. If the water recedes, more should be added. If mole crickets are present, they will soon float to the surface.
These methods are not likely to be effective in uncut grassland where prairie mole crickets are found. The most effective survey method for this species is listening for calling males during the mating period (April and May). Males call for about 50 minutes, beginning 5 or 10 minutes after sunset and ending rather abruptly once it is dark. Once a male is heard, the burrow can be located. This species should not be controlled and specimens should not be collected unless there appears to be a good population at the site.
The northern mole cricket only occasionally causes damage to turf in Oklahoma. The most serious problems have been reported on golf greens in the form of root damage, tunneling, and soil excavation (interfering with ball roll on the greens). The major control effort should be directed at the young (nymphal) stages. Because hatching may extend through June, late June or July treatments should be considered to reduce mole cricket populations (at the earlier, more vulnerable stage). It is generally best to apply insecticide late in the evening. In general, mid to late July treatments are best (repeated if necessary). In some highly maintained areas or in sod to be cut in spring, April treatments may reduce damage from overwintered mole crickets.
Turf that is well maintained recovers more quickly from mole cricket damage than poorly maintained grass. In some cases, it is possible to roll grass damaged by mole crickets and have the turf recovered because roots are pressed back in contact with the soil.