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|Crayfish Chimney in Lawn
(Photo by Tim Gibbs)
(Photo by Peggy Sellers)
When rain and flooding brings lots of water, you may find crawdads where you think they don't belong. These crustaceans are also referred to as crawfish, crayfish, mud bugs, or stonecrabs. They look like miniature lobsters.
There are about 300 species of crayfish in United States. They are used as fish bait and for human consumption. Crayfish can cause damage in turfgrass when they burrow in high moisture soil, creating muddy, hollow columns called chimneys. These chimneys dry and become very hard as they bake in the sun.
The crayfish commonly emerge at night to roam about the turf. They have 10 legs with the front pair enlarged into chela, or pincers which are used for prey capture, feeding, mating, and defense. The other four pairs of legs are used primarily for walking and food handling. Crayfish feed on organisms such as snails, algae, insect larvae, worms and tadpoles.
Heavy, low lying soil, especially near ponds and streams, is more likely to be damaged by crayfish, than high, well-drained, light soil. Numerous chimneys in a lawn are unsightly and interfere with mowing, dulling lawn mower blades.
Control of crayfish is difficult. To eliminate crayfish, the area usually must be tiled and drained. However, where the water table is high draining will not solve the problem. Some people cope with crayfish lawn problems by allowing those areas to revert to marsh or wetland areas. Solid wood or stone fences that fit tight against the ground have been used to reduce the migration of crayfish to fine turf areas. There are no general use pesticides for crayfish control. Capture is the most popular method of control (watch out for those pincers!). Wire cage traps can be baited with fish, chicken, or other meat and can be used to capture crayfish, however these are not usually cost-effective.
Plant and Pest Digital Library and Digitally Assisted Diagnosis, Purdue University, West Lafayette, Indiana.