Moles have returned to the soil surface from their overwintering depths. Consequently, tunnels and mounds are showing up in the lawn. See the picture below and our online article in the HHPN Encyclopedia.
One of our biggest frustrations with moles is the perennial misinformation that an insecticide application to kill grubs will solve the mole problem. This is the “lie that will not die.” Forty years ago, it might have been true that an insecticide application would discourage moles because back then, the insecticide ingredients being used were highly toxic to people, pets, and wildlife, but they were especially toxic to the “Mole Main Meal” – earthworms.
All pesticide that were highly toxic to earthworms were discontinued or banned long ago. Insecticides available today do not kill earthworms; therefore, the white grub treatment does NOT remove the mole food source
The over-simplistic, bad advice to use an insecticide for mole control often comes at the wrong time of the year. For example, when there are no grubs in the lawn. Further, springtime, when moles are first noticed, is NOT the time to apply grub control insecticides as white grubs are still deep in the soil and they are fully grown, two conditions that will make them nearly impossible to kill. An unnecessary application of pesticide wastes time and money without doing anything to solve the original problem.
For an example of the importance of understanding pest habits see the ISU Turfgrass article from April 8, 2020, by Nick Christians and Adam Thoms. Wildlife damage to ISU intramural sports fields looked like the digging that occurs when raccoons or skunks dig to feed on white grubs. See the photo below. Except this damage occurred in November and again in March, times when white grubs would not be expected to be at the soil surface. Inspection and shoveling confirmed there were no white grubs present. It turns out this was raccoon digging damage. But there were no grubs. Just earthworms. Insecticide would have been worthless. Instead, traps were used to capture the offending raccoons.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on April 10, 2020. The information contained within may not be the most current and accurate depending on when it is accessed.