Soil Mounds and Mole Tunnels

Jim Parkhurst, Associate Professor and Extension Wildlife Specialist; Virginia Tech College of Natural Resources and Environment

Inquiry: Mounds of soil are regularly appearing and becoming more prevalent in this zoysiagrass lawn as the heat and drought of the summer progresses. There aren’t any visible holes to associate with digger wasps or other insects, and no strong indication of tunnels from either moles or voles either? Can you help with an identification of what you think is causing this damage in a zoysiagrass lawn?

Dr. Parkhurst: Moles (especially the star-nosed mole) are notorious for pushing up mounds of soil excavated when creating their feeding tunnels. However, for some species (e.g., the Eastern mole), it’s more common to see the entire underground tunnel being raised up, not just a few mounds. Yet, if you look carefully in the photograph (above) showing multiple soil mounds across the lawn, you actually can trace the location of several underground feeding runs between some of these mounds by tracing the discoloration of the grass … the affected areas look browner, probably from the desiccation resulting from the root system being disturbed, but the tunnel may not have been raised enough to detect.

mole mound

This looks like very dry, porous, granular soil as well, which may not provide much structural integrity to retain support of a tunnel and even the mounds don’t look to be a large and elevated as one might normally expect to see. I suspect that, if one carefully dug across one of these lighter discolored swaths, you might find the remains of the underground feeding run that was created.

For suggested treatment, see the newly-revised Virginia Cooperative Extension publication on Managing Human-Wildlife Interactions and Moles on the VCE website.