There are many ways in which you can tell if your lawn has grubs. First of all, grubs will cause your grass to turn slightly yellow. When they are eating the roots, then your lawn is going to get less water. Grubs will also come out at night and eat grass that is touching the surface of the soil. Grubs have chewing mouth parts, that allow them to digest your grass, and they will turn green after they have feasted on your lawn
Another sign is if the grass rips out easily. Usually, this is because the lawn grubs will eat some of the deepest roots first. And there isn’t much to hold your grass in place.
If you have had a bad infestation of grubs in a sod lawn, you may have three quarters of an inch of dead sod in areas where the grubs have been. You typically don’t see the spots until the end of the summer, or the beginning of the fall. By this time, it is probably too late in the year to treat your lawn for grubs. But you can treat your lawn for them early in the spring next year. You may even want to consider using a pest control company.
A third sign of grubs in lawn, is if you have gophers digging up your lawn, or you have birds picking holes in your dirt. They are not actually trying to damage your lawn, they are just trying to get lunch. And they really like eating grubs.
If you are experiencing any of these signs, it is a good idea for you to check for grubs. To do this I usually go to the worst area of lawn, and pull up dead sod in that area or on the edge of that area, and I look for white grubs. These grubs will be ½ to ¾ inch in length. They are white, and do not look like an earthworm because they are short and stout. If you do find them, you will want to treat your lawn immediately. Hopefully, you’re treating it soon enough, you can prevent them from doing any worse damage your lawn. You may also want to apply the treatment twice, to kill unhatched grubs which will be immune to poison the first time you apply it.