It could be that the moles are trying to tell you something. When they dig burrows under lawns it’s usually to eat the grubs of cutworms and larger beetles.
During the winter months, these juicy morsels tempt moles to dig where they would not normally do so. Grubs are very damaging; they eat at the root system of your lawn, resulting in dead patches. Moles are actually doing you a favour by preying on the grubs and are likely leaving behind less damage than if they left the grubs alone.
It’s understandable that you don’t want your lawn torn up. However, if you deter the moles without dealing with the reason they’re there, more moles will simply move in for the food source.
An environmentally friendly method of deterring moles is to plant castor oil plants and drench the soil around mole tunnels and mounds with castor oil. Moles will not cross a castor oil barrier. You can make the castor oil go farther and get the same results by diluting it with water. In late fall, spray the border around your lawn with castor oil. A 5-centimetre strip should be sufficient. In late summer, check your lawn for brown spots of dead grass which would indicate that grubs have been feeding on the roots of your grass. If so, double your spray of castor oil. You can also try placing an empty soda bottle near the entrance to one of their holes – the sound of the wind in the bottle can scare the moles off. Assuming the moles are after grubs, you’ll also need to deal with your grub problem.
Parasitic nematodes are living organisms of microscopic scale that will kill the unwanted grubs. Because the nematodes are alive, they must be handled with care. Read the instructions on the package very carefully. As a general rule, keep them cool at all times until they are moistened just before application. Do not let them sit in water and do not expose them to light (UV). Water the grass before application and then spray the nematodes on the lawn with a sprayer on an overcast day, or in the evening when the temperature is at least 15˚C, and keep the soil moist. Nematodes need to be placed where the grubs are and should be applied across the whole lawn, rather than in spot applications. You will have more success if the nematodes are applied when the grubs are small. This is often in the spring and late summer, but double check the grub you are dealing with and its life cycle to be sure.
