Insects are not a common cause of residential lawn damage, but certain species occasionally damage or kill turfgrass. Insect feeding can cause grass to turn yellow or brown, or die, especially if the grass is already stressed. Damage usually begins in scattered small patches, which may merge into large dead areas.
Lack of proper cultural care and use of inappropriate grass species in a particular location are more likely responsible for unhealthy or dying lawns than insects. Disease-causing pathogens, excessive or inappropriate use of chemicals such as fertilizers and herbicides, and dog urine also produce damage resembling that of insects. Before taking any insect control action, be sure that it is insects causing the problem and not something else.
Insects that do infest home lawns are often difficult to observe and their presence goes undetected until significant damage has been done. Plus, insect damage can be mistaken for other problems such as drought damage. If the lawn remains brown or shows signs of thinning despite appropriate watering, then closer examination for insects should be done. A lawn inspection should include looking at leaves, stems, roots, thatch and the soil to determine if the problem is insect-related and catch the problem before extensive damage occurs.
Insects that may cause damage lawns include various root-, crown-, and leaf-feeding caterpillars; white grubs, which are the larvae of beetles; billbugs, which are weevils with white, grub like larvae; and chinch bugs, which are true bugs in the order Hemiptera. Armyworms, cutworms, mole crickets also cause damage to lawns. In northwestern America, cranefly are sometimes a problem.
Each species produces somewhat different damage symptoms and must be managed differently. Many insects may be observed while examining grass. However, control is rarely or never needed for most types of insects because they are harmless, and more likely to be beneficial.
Common beneficial insects include predatory ants, ground beetles, rove beetles, and blister beetles. Other common arthropods that are primarily decomposers and do no significant injury to turfgrass include springtail's and millipedes.
Good cultural practices are the primary method for managing insect damage to lawns. Growing appropriate grass species for a particular location and providing lawns with proper care are especially important. Practices such as irrigating and fertilizing have a major impact on lawn health. Physical controls, such as thatch removal, choice of mowing height and frequency, and providing grass with more light by pruning tree branches, are also important in certain situations.
Most home lawns do not need to be treated with insecticides if proper cultural practices are followed. Insecticides should never be applied unless a pest is identified and detected at damaging levels. If insecticides are necessary, choose materials that have minimum impacts on beneficial organisms and the environment.
Keeping your grass healthy is by far the best way to prevent damage from lawn pests. Healthy lawns require few, if any, insecticide treatments. If a lawn is under stress and a pesticide is applied, it stands a better chance of suffering damage from the pesticide itself.