Grubs are, basically, baby beetles, mostly Japanese Beetles and Masked Chafer Beetles although there are many varieties. In July, adults look for a good place to lay the eggs for the next generation of beetles, and, all too often, it ends up being your lawn. At the end of July or beginning of August, the eggs hatch and the grubs begin to feed on the roots of the grass in your lawn. Then, they lay dormant through the winter, eat more roots in the spring and reach adulthood in late June or early July to start the cycle over again. Not only are grubs voracious eaters, they are also like an all-you-can-eat smorgasbord to many different animals. A heavy infestation can be detected either by irregularly shaped brown and dead areas in your lawn, or the signs of excessive digging by smaller animals, such as skunks, raccoons and moles. Dogs have also been known to dig in the yard for a light grubby snack.
Why My Yard?
Don’t take it personally. Beetles are insects that travel, for the most part, where wind and whim carry them. However, there are certain characteristics that they look for when searching for a place to lay their eggs. Access to a food source is very important. Japanese Beetles, in particular, like to munch on ornamental plants. If you see a lot of adult beetles in your yard, dining on the landscape, most likely they are also laying their eggs in your yard. Another consideration is water. July can be a very dry month in many parts of the county and if you water your lawn to keep it green the ground will have a lot of moisture, which will attract the adults.
How Do I know if it’s Grubs Killing my Lawn?
There are many different things, both natural and artificial, that can kill the grass in your yard. There’s a way to find out if grubs are the culprit. In August select several different areas of your yard, especially on the outside edges of the areas that are brown and dieing. You can use a bulb planter, cup cutter or small shovel to investigate the area. A bulb planter or cup cutter is going to be about 1/10 of a square foot. When you pull up the soil, spread it out on a piece of cardboard and count the number of grubs in the sample. Multiply the number of grubs found by ten to find out how many there are in one square foot. If you are using a shovel, cut three sides of a square, each side measuring twelve inches, and pull back the layer of turf. Again, count the number of grubs, then replace the turf and water the area so it will grow back.
Some grubs are to be expected in almost any yard and are a part of the natural order of things. It’s the concentration of grubs you are trying to determine. If you find zero to five grubs, you’re okay and can rest assured that there’s something else affecting your lawn. If the count is six to nine, there’s a bit of overpopulation and may be the reason animals are digging up your yard to find food. If there are ten or more grubs per one square foot, then they are eating the roots of the grass down to nothing and killing the lawn.
OK, it’s Grubs, What Do I Do?
August is most likely the month that the grubs will be closest to the surface and most susceptible to attack. There are many natural and artificial products that you can use to cut down on the grub population. The most common natural substance is going to be something that contains nematodes. These nematodes are a parasite that live on grubs, but will do no damage to the yard, especially if you use them according to directions. They will infest and kill the population and save your yard. If, when you check for grubs as mentioned above, and you find many of them to be brown and/or dieing, you may just want to let nature take its course to bring your beetle problem under control.
There are also many products that you can buy in any lawn and garden center that will control grubs and many other insects that may infest your yard. Again, be sure to use them according to the instructions and warnings on the bottle as many of them are also hostile to humans and animals, too.