The answer to 'why is my grass pests' is that your grass may be infested with various pests, such as grubs, chinch bugs, sod webworms, or other insects. These pests can damage the roots, stems, and leaves of your grass, leading to discoloration, thinning, and even bare patches.
Common symptoms of grass pests include irregular brown or yellow patches, wilting or dying grass, and the presence of insects or larvae in the soil. To diagnose and treat the problem, it's important to identify the specific pest causing the issue. If the problem persists or you're unsure of the cause, it's best to consult a professional landscaper or pest control specialist.