Visible Clues
Knowing your local pests and their life cycles is the key to determining whether lawn damage is due to insects or not. The rest is a matter of keeping your eyes open. Most insects are large enough to be visible, so don't wait for your grass to start dying to find out if there's a problem.

Some evening, the presence of sod webworms may become apparent when you see their adult form, a buff-colored moth, zig-zagging across the lawn. And consider those June beetles banging against the screens at night or the Japanese beetles eating your roses--they should alert you to the fact that their larvae may be damaging your lawn's grass roots. Another clue to the presence of underground insects is small upturned areas where skunks dig by night and birds congregate by day.

Looking closely at the lawn, even using a magnifying glass, will enable you to see signs of chewing or the tiny light spots indicative of sucking insects. You might also note the tunnel openings of mole crickets or actually see thatch-level insects such as armyworms, chinch bugs, leafhoppers, and aphids.

Becoming an insect sleuth isn't difficult, and your persistence will pay off. The byword here is vigilance--making a regular habit of closely observing your turf. And remember, just a few bugs are nothing to worry about. You only need to take action when the population approaches damaging levels, remembering that extermination is not a reasonable goal.