The answer to 'why is my grass pests' is that your grass may be infested with insects, weeds, or other pests that are damaging the lawn. Common grass pests include grubs, chinch bugs, sod webworms, and crabgrass. These pests can cause discoloration, thinning, and patchy growth in the lawn.
Symptoms of a grass pest problem may include brown or yellow patches, irregular growth, or visible insects or larvae in the soil. To solve the issue, you'll need to identify the specific pest and take appropriate treatment measures, which may involve applying pesticides, removing weeds, or aerating and overseeding the lawn. For severe or persistent problems, it's best to consult a professional landscaper who can properly diagnose and treat the issue.