Many insects live in or on lawns, but only a few damage lawns enough to require control measures. Insects may feed on roots, stunt the grass or cause dieback, browning or bleaching of leaves. If you see symptoms, identify the pest before trying to control it. Having diverse, healthy plants in the lawn and landscape will discourage pests and will attract birds (which prey on insects) and other animals. This should be your first line of defense against pest insects.
Grubs are the major insect problem in Maine, but populations really aren’t high enough to visibly damage turf. Common grubs are the larval stage of June beetles, Japanese beetles, Asiatic garden beetles or European chafers.
A healthy, properly watered lawn can tolerate about 10 grubs or up to 30 chinch bugs (another potential lawn pest) per square foot. Beneficial nematodes are effective against grubs but must be applied according to directions in order to work. They may not survive in colder parts of Maine. Milky spore disease targets Japanese beetle grubs, but is not very effective in Maine. If you see Japanese beetles with eggs growing from their thorax, do not kill them. These beetles have been parasitized by tachinid flies. Each egg will develop into a new fly, which will parasitize more beetles, and so on.
Turf diseases are seldom serious problems in Maine. Occasionally leaf spot, brown patch or a pythium disease appears, but seldom do these justify chemical treatment. Most often, by the time the disease is identified, the weather has changed and the disease has stopped spreading. Compost can confer resistance to dollar spot, brown patch, pythium and other diseases in turf.