So You've Got Bugs
Having done your homework and identified the particular insects damaging your lawn, you now must decide what, if anything, to do about them. There are general guidelines for how many insects in a given area constitute a threat. The tricky part is that vigorous lawns can withstand greater numbers of pests than those under stress. Thus a healthy lawn might not show signs of injury in spring despite having a high number of Japanese beetle grubs per square foot. But the same lawn, when semi-dormant in late summer, might develop significant problems with just 6 to 10 grubs per square foot. Before making treatment decisions, consider how healthy your lawn is to start with, where the insect is in its life cycle, and how much damage you can tolerate.

If the population numbers and extent of grass injury warrant action, your first step might be to physically remove as many bugs as possible. (See "Mechanical Bug Removal.") Next, reduce thatch levels and compaction where they are problems. You should also consider whether your lawn needs some extra tender loving care to help it recover more quickly. Don't cut it too short or add water stress to its list of woes!

If, despite your best efforts, pest populations aren't restrained through the more benign efforts of cultivation, grass selection, and competition from beneficials, you may need to use microbial controls, botanical insecticides, or insecticidal soaps. These have the environmental advantage of rapidly breaking down when exposed to sunlight, heat, and water; so they don't persist on vegetation or in the soil. They generally are considered less-toxic to humans than synthetic products, but they can still upset the ecological balance in your yard and cause more harm than good if used improperly. Be sure to read labels and follow directions carefully, including the use of protective masks and clothing--some of these substances are severe irritants. When using sprays, avoid the middle of the day when they will be less effective, and time applications to take advantage of pest life cycles. Check with your local Cooperative Extension Service to learn about the specifics for your location and pests.