The people at Recreation Services contacted us about damage to sports fields on campus that was occurring in mid-March. It appeared to be secondary mammal damage from feeding on insects in the turf area. While that is not unusual, the timing was different that we are used to. This usually occurs in August to October when Chaffer grubs are active just under the surface of the turf. Skunks, raccoons, and other mammals often tear up turf at that time, but March is very unusual. Adam Thoms, Nick Christians, and Donald Lewis (entomology) visited the site in late March to see if there was early emergence by grubs. We didn’t see any grubs, but there were a lot of earth worms just under the surface. Dr. Christians and Lewis both have 40 years of experience looking at turf damage in Iowa and never have we seen damage from animals feeding this early on earth worms. The staff set up a trail camera and live traps to catch the perpetrators in action.
It was raccoons. They were easy to live-trap. A quick check of the literature on raccoons showed that they will eat earthworms if they are hungry enough.
So, while this was a first for us here at Iowa State University, it does occur and may be something that you will want to watch for in the future.
Two more pictures from late March
Here are the culprits.