"I don't remember when they did not come anymore"

Milton Hans, born in 1892, lived on Church Street in Northbrook, Illinois. From there he drove his cows to pasture. He wrote this recollection about crayfish, now in the archives of the Northbrook Historical Society,
in 1956.

"In the years when I used to drive cows to pasture in summer and would be barefoot most of the time (because the skin grew back (free) on the bottom of the feet, but shoe soles cost money to replace), [I] remember that after warm heavy rains that the ground and especially the road would be almost covered with what we called crabs — others call them crawfish. It was hard to walk without stepping on some for a while after a shower. I do not know where they came from in such numbers, but do not believe they rained down as some of them would certainly have hit a person if they had. I think that the heavy rain ran into the holes they had in the ground and forced them out. I don’t remember when they did not come anymore but realized at some time that I didn’t see them anymore after a shower."

Grassland Crayfish: Burrowing Deep
by Mike Redmer

e often think of crayfishes as living in water. However, in Chicago Wilderness, three crayfish species surprise us when their burrows show up on dry land. The most common of our burrowing species is the prairie or grassland crayfish (Procambarus gracilis).

Adult grassland crayfish average 2-3 inches long, with bodies of rusty brown color, and powerful pincers, which often have a slight olive-green upper surface. Mating may occur year-round, but is probably most frequent in spring and early autumn.

In the Chicago region, females are usually found carrying embryos or young in March through May, after which the young drop from their mothers’ abdomens and begin growing rapidly. This species normally lives a maximum of three or four years.

The name "grassland" crayfish is somewhat misleading. While Procambarus gracilis often is abundant in wet prairies, grasslands, grassy ditches, and marshes, a recent study in Illinois showed that it also frequently occurs in temporary pools and ponds located in woodlands. Most large populations of grassland crayfish occur in areas of clay, silt, or loam soils, or where clay "hardpans" lie under richer organic soils. In these areas, the presence of crayfish is easily determined by their conspicuous burrows.

Crayfishes excavate burrows by using their pincers to plow soil to the surface, where it may spill over to form spoil piles or even small "chimneys" at the burrow entrance. Because crayfishes breathe with gills, they must always maintain some degree of contact with water, and burrows usually extend deep enough that the occupant can retreat to, or below, the water table. In the case of the grassland crayfish, burrows can be six feet deep, or more. Thus, in areas where pond hydroperiod or water table depth is unpredictable, deep burrows are important retreats in which the crustacean occupants can wait for rain and conditions that allow brief overland movements. These movements are most likely to occur on warm and humid (or rainy) days or nights in spring and summer. Stewards, naturalists, and others who prowl Chicago Wilderness on rainy days often encounter small crayfishes plodding clumsily across the ground.

While crayfishes are among our most recognizable invertebrates, surprisingly little is known about their biology. Of particular interest is the role they may play in the health of local natural communities. There is general agreement that grassland crayfish (and other burrowing species) may be important symbionts of animals that use the crayfishes’ burrows as retreats or places to hibernate in winter. Among these are several prairie or wetland snakes such as the rare Massasauga and Kirtland’s snakes.

Crayfishes are omnivorous scavengers, but perhaps more importantly they are frequent prey of a number of larger predators, including raccoons, wading birds, large fishes, turtles, frogs, and snakes. A considerable amount of burrowing crayfish habitat has been lost due to the draining of wetlands and the development on prairies. Yet, some local populations remain large, indicating that the grassland crayfish and some of its burrowing relatives have so far been successful in Chicago Wilderness.