Kathleen Cue, Nebraska Extension Horticulture Educator 

It’s been a good year for moles.  A nice amount of rain keeps soils moist and workable—the perfect environment to enable mole movement as they “swim” through the soil. Many people approach the problem of moles by focusing on grubs—that if the grubs are gone, then moles won’t be in the lawn. Though not accurate, it leads to grub control measures that do little to minimize mole activity.  

In studies that examined the contents of mole stomachs, earthworms dominated as the preferred food choice, with ants being a distant second. Those involved with wildlife damage management are aware of this, utilizing toxic baits that replicate earthworms’ odor and taste. Because moles are insectivores, they won’t eat poison peanuts or chewing gum.   

Moles create two different types of runs—a daily use tunnel that gets re-used and then the forage tunnel that is used once and abandoned. The only way to know the difference between the two is to first step down all tunnels.  The ones that are bumped up the next morning are the daily use tunnels. This is where earthworm mole-killer baits or harpoon traps should be placed. A repellant utilizing unrefined castor oil is another option to move moles out of the area.

The immature stage, the grubs, of masked chafer, May/June and Japanese beetles are the main culprits behind insect damage to lawns. As adults, masked chafer and May/June beetles do little in the way of damage to plants. Not true with Japanese beetles, who especially enjoy feeding on roses, linden, birch and grape. Control measures for Japanese beetle grubs as a strategy to minimize damage to landscape plants from adult beetles later simply doesn’t work because beetles fly in from other areas.

For lawns, it’s good practice to focus management tactics when grubs are actively feeding. While we see grubs during spring planting projects, grubs are causing little in the way of feeding damage, instead devoting energy to pupation to then emerge as adult beetles. It is the next generation of grubs where damage to lawns can be extensive because the younger instars (the stages of development) are actively feeding, severing turfgrass roots.   Products containing the active ingredient chlorantraniliprole can be put down on lawns in early July to target grubs while they are small and do not harm pollinators.

Go to Dodge County Horticulture Web page for more gardening information.

Photo: Grub
Grub Image