Fleas and chiggers are both pests that can infest the lawn and cause great discomfort to both humans and animals. Fleas are tiny insects that feed on the blood of a host. They can also transmit diseases. Chiggers are the microscopic larvae of mites and feed on the fluids in tissue. The saliva of fleas and chiggers can cause an allergic reaction in humans and animals that takes the form of weeping red welts and painful itching. Killing the fleas and chiggers in your yard will reduce the chance of you or your pet being bitten.
Walk around the lawn in white, knee-high socks. You will be able to see the fleas jump onto the socks. Chiggers are microscopic, but where there is one there is likely to be the other. Take note of any "hot spots" in your yard where flea activity seems especially fierce.
Clean up the lawn. Before you apply any flea and chigger treatment, get rid of the places they like to hide. Mow the lawn short, and remove any piles of decaying foliage. Get rid of standing water or marshy areas, which is where both pests like to breed.
Kill the fleas and chiggers with a pesticide. Use a spray application for best results. For large yards, use a pressure sprayer. Look for a pesticide that contains premertrin, diazinon, cyflurhrin and carbaryl, which will kill the pests but do not harm the grass. Apply the pesticide only to the "hot areas" of the lawn and the areas where pets are likely to frequent, such as along a dog run.
Reapply the pesticide after two weeks, as many do not kill flea eggs. This will kill any fleas that have hatched since the first application.