Lawn Insect Pests

- Follow a few simple rules to avoid most lawn damage from pests -

Summary: Healthy lawns can tolerate considerable damage from insect pests. Proper irrigation, fertilizing and mowing are far more important than pesticides to control lawn pests. Follow these simple rules and prevent most problems from lawn insects.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

Which lawn pests cause damage?

There are many insects that can potentially damage lawns in the US. If you need a comprehensive review of all pests see the book listed below. For many of us, however, the following few are the most important ones you'll deal with in our home lawns.

  • Crane flies (right) are emerging pests in some parts of the US and can be particularly damaging to newly planted lawns. Crane fly larvae feed on grass roots during cool parts of the year and can kill large patches of lawn as temperatures rise and the soil dries out, see Crane Flies for identification and control of these lawn pests.
European crane fly adult

European crane fly adult ~ 1-1/2 inch long.

  • Mole crickets are lawn pests mainly in the warm, humid southeastern states. They burrow in the soil making characteristic raised bumps on the soil surface. This burrowing causes physical damage to soil and lawns, see Mole Crickets for identification and control guidelines.
  • The larvae of lawn moths feed at the soil surface on grass stems and leaves. A few moths/larvae are generally no reason for concern if the lawn is otherwise healthy (see below).
  •  Chinch bugs small insects that feed above ground on grass blades. Chinch bug damage tends to be much more severe during dry/hot summers. If you suspect chinch bugs take a look at out Chinch Bug page for identification and current control information.
  • Finally, and potentially the most destructive are white grubs. These large beetle larvae feed on grass roots causing considerable damage and dead patches. The larvae are the immature stage of beetles like Japanese beetle which can also cause significant damage as adults, see White Grubs for control suggestions.

Lawn care "rules"

The most important thing to keep in mind is: healthy lawns can sustain and outgrow most damage from lawn pests. This means that by following a few simple rules you can avoid most lawn pests and diseases without using pesticides. The three most important rules for successful home lawn care are:

(1) Don't over water or over fertilize - grass will be more susceptible to insects and disease if forced to grow too quickly. Allow grass to go through a natural wet/dry cycle between irrigation. Or, simply stop watering in early summer and allow grass to go dormant during the dry months.

Most lawns need far less fertilizer than they get each year. The excess fertilizer runs off and pollutes rivers and lakes or forces the grass to grow too fast making it susceptible to lawn pests. Established lawns only need a light application of fertilizer twice a year in the spring and fall.

(2) Test the soil at least every 5 years and add lime and micro-nutrients as needed. This is probably the most overlooked aspect of lawn care. Check with your local Cooperative Extension office (google "your state name"+"your county name"+"Extension" for the office in your county) about where you can get your soil tested locally for a small fee. Yearly applications of lime (dolomite lime, not hydrated lime) are needed in many areas in addition to micro-nutrients.

(3) Mow at the proper height for your grass type but most importantly don't cut the grass too short. Many turf managers mow at the highest setting possible for their equipment. Your grass needs some leaf surface (grass blades) in order to be healthy!

If you follow these simple guidelines your grass can resist damage from many insect pests and diseases without using insecticides or fungicide. Plus, if an insect pest or disease does creep in, the lawn will be healthier to begin with and it will be easier to treat the problem.

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