How to identify the pests that are damaging your lawn
What is wrecking your lawn? It could be skunks, raccoons, moles, voles, pocket gophers, or lawn insects. Each leave behind evidence and signs of their presence.
Skunks are out at dusk, during the night, and at dawn in residential areas searching for food, water, and shelter. In the lawn, they dig small pits, make cone shaped depressions from three to five inches across and roll back sod in search of lawn insects, caterpillars, grubs, earthworms, small rodents, snakes, lizards, frogs, and mushrooms. Skunks are preying on animals and insects that may themselves be causing damage to your lawn.
Moles are insect-eating mammals, between five and seven inches long, that live almost entirely underground in shallow tunnels. They damage your lawn by burrowing. They leave behind round mounds of dirt at tunnel entrances, dislodge plants, and cause under-surface ridges.
Voles are meadow mice, or mouselike rodents, that live mostly above ground but do some burrowing. Voles, when they are substantial in number, create distinct runways that lead to those burrows.
Gophers, also known as pocket gophers for their large cheeks to hold food and nesting material, can cause considerable damage in your yard. This gnawing mammal has strong, constantly growing incisors. It can make several mounds a day under your lawn. A gopher is larger than a mole, and so too is the size of its tunnel. The mound of dirt outside the entrance to their tunnels is in the shape of a half-circle; the mole’s tunnel entrance is a full circle.
Like skunks, raccoons dig up turf with their sharp, non-retractable claws searching for grubs and other insects. Raccoons are omnivores with a diet that includes fruits, nuts, insects, small animals, fish, and even carrion. Raccoon grub-hunting activity is often most noticeable in late summer and fall when grubs are abundant. To manage these harmful vertebrate predators, do not attract them by providing shelter or food. For further information about these landscape pests, search for UC IPM Pest Notes on Racoons.
Other lawn damage may be from lawn insects feasting directly on the grass or living in it. Insects are not a common cause of lawn damage. If there is damage to your turfgrass and no evidence of a vertebrate predator, you will have to dig into the lawn to find the cause.
Lawn insects that eat the turfgrass directly are root, crown, or leaf-feeding caterpillars. There are various larvae that become white grubs such as the one-inch, C-shaped larvae of a scarab beetle, that feed on plant roots or decaying matter. The larvae of masked chafers are also white grubs that feed on roots. Weevil larvae, or billbugs, are chewing insects. Cinch bugs are distinguished by their piercing and sucking mouthparts, which cause significant damage by sucking plant sap and injecting toxins leading to yellowing and death of grass. Crane fly larvae, also known as leatherjackets, have a segmented worm-like body that eats roots and can damage lawns.
The following website is a diagnostic tool from University of California Agriculture and Natural Resources and the Statewide Integrated Pest Management to assist in identifying and determining turfgrass problems. ipm.ucanr.edu/TOOLS/TURF/PESTS/diagnose.html
Have a lawn maintenance or other gardening question? Use the “Ask a Master Gardener" tool to submit the details and a UC Master Gardener of El Dorado County will get back to you during office hours.
This article by UC Master Gardener of El Dorado County Kit Smith originally appeared in the September issue of Village Life.