Crawfish, or crayfish, Procambarus sp. Ortman (Decapoda), can be a nuisance pest in Louisiana lawns. They typically reside in areas with permanent fresh water; however, some species can live in areas near waterways or in areas that only occasionally hold water. Though crawfish do not technically injure turfgrass, they do burrow in the soil and create cylindrical “chimneys” made of soil, which some homeowners may find unsightly in the lawn. They are commonly observed in the spring.
Crawfish look similar to miniature lobsters and are red to rusty brown in color. They have two long antennae that extend from their head and beady black eyes. Along the underside of their body, they have a set of two large claws and four sets of legs. Reproduction typically occurs in the spring and early summer when mature males and females mate in open water. After mating the female typically burrows down into the soil to spawn. Hatchlings emerge about three weeks later. Hatchlings will molt, or shed their exoskeleton, several times as they mature into adults. Regardless of maturity, all crawfish burrow into the soil to seek out water. Burrows provide a humid environment and also protect them from predators.
One way to reduce pest injury and accelerate turfgrass recovery is to maintain a healthy lawn through proper cultural practices. Never apply more than 1 pound of nitrogen per 1,000 square feet per application and always follow soil test recommendations for proper fertility. Irrigate as needed while taking rainfall into account. Mow regularly, but never remove more than one-third of the leaf blade height at one mowing. Thatch can develop over time and may need to be reduced through vertical mowing. Compaction can form more quickly on finer texture soils and in areas where there is high traffic. Dethatching or aeration need to be performed in late spring to summer when the turfgrass is actively growing. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass and can increase tolerance to pest injury.
There are no pesticides currently labeled for crawfish control. Some species of crawfish are considered endangered, and the use of chemicals near water can potentially contaminate groundwater and local waterways; therefore, the use of chemicals to control crawfish is illegal.