By: Patrick Troyer, Paulding SWCD
Have you ever noticed that your grass pulls up off the ground like a loose piece of carpet? Chances are that you have the pest that is the focus of this week’s column, grubs. What are these creatures of nature and how do they impact your environment? How do you control their impact? These questions and more will be answered as we look at yet another feature of our natural environment.
Grubs are premature insects, usually of the beetle family commonly found underground feeding on the roots of certain species, particularly the grass on your lawn. These worm-like organisms appear about one inch in length with a grayish-white body with a brown head. When they are disturbed, grubs will curl up into a “c-shape”, one of the key identifying characteristics of the grubs. According to the Missouri Botanical Garden, grubs will feed on the roots of grass for a period of one year or even more, all depending upon the individual grub species.
Grubs, like many other insects, go through a series of changes in their life known as metamorphosis. Metamorphosis means to “change form” and typically includes an egg stage, larva stage, pupa state, and the adult stage. According to the Missouri Botanical Garden, there are annual grubs which will go from an egg to an adult during one year while there are also May or June beetles which will take two to three years to complete a generation where they will feed below ground before they emerge as an adult. Eggs are laid within the first few inches of soil that is moist and warm with the white larvae (grubs) emerging from the eggs within two weeks. The grubs them start to deed on any organic matter such as the roots of your grass. The Missouri Botanical Garden writes that once soil temperatures begin to decrease upon the arrival of fall, grubs will go deeper in the soil and enter a state of hibernation.
With the arrival of spring, annual grubs will come to the soil surface where they will feed on the grass until May and then complete its life cycle at that point with the emergence of the adult beetle. According to the Missouri Botanical Garden, the May or June beetle will feed on the roots for another year or two, emerging as adults by the second or third year of their life cycle.
Grub damage is easy to spot on your lawn, although you may not see obvious signs of the grubs themselves since they do most of their feeding below the surface. The Missouri Botanical Garden says that one thing to look for on your lawn is patches of thin spots of grass and then dead patches even if adequate rainfall has been received. These dead patches can easily be pulled up much like a loose piece of carpet. It is also common to see your pet dog digging up the yard a lot as this means they are detecting grubs or a large flock of birds feeding around the dead patches. To determine that it is grubs which are the cause of the damage, make sure to take a shovel to turn over the grass for actual presence of the white colored grubs that often curl into a c-shape.
How are they controlled and prevented? The Missouri Botanical Garden provides several tips that can be used to control this organism. First, get an idea of just how bad the damage is. If you notice less than ten grubs per square foot once you peel back the grass, it is not recommended to take control actions. Next, make sure you are keeping your lawn healthy with recommended amounts of fertilizer or water as this may not keep the grubs from your lawn, but your lawn will be able to bounce back from any grub damage. The Missouri Botanical Garden writes that you don’t want your lawn to be watered too much especially during June or July when the adults are on the search for green grass to lay their eggs. If you reduce your water use during this time, it is possible that the number of eggs laid in your yard could be reduced. Of course, it is always a good idea to let rainfall water the grass as much as possible.
Always try the biological methods of prevention mentioned above first, but there are chemical methods available as well. Only use this method if grubs are spotted more than ten per square foot in July or where there is a history of damage. The Missouri Botanical Garden recommends that any chemical application take place in July or August with a spring treatment not recommended. Grubs are something that not all of us want to see but something that we can easily identify and control to have a healthy landscape.
