White Grubs: Is Your Lawn Feeding This Pest?
They do not come to the surface, so you may never see them unless you dig in the dirt to plant flowers or shrubs. The bloated larvae of common beetles are a normal part of the ecosystem in most lawns and no cause for alarm in small numbers. In higher numbers, however, they can inflict visible harm on your grass. Learn to identify indigenous white grubs and their damage to determine if your lawn is feeding an underground horde of uninvited pests.
The first clue of a fall white grub problem can be found in the past summer’s beetle population. White grubs are the larvae of green June beetles, Japanese beetles, May or June beetles, and chafers.
If you noticed an unusually high number of these pests buzzing around your home this summer, your lawn may be serving as a banquet to their offspring now.
Grubs munch below the soil surface, primarily feasting on grass roots. Since roots supply water and nutrients to the grass blades, grub damage typically results in yellow or brown leaves. The effect can mimic drought stress, even when rain or irrigation is plentiful. Heavier infestations result in loose turf that can be easily lifted from the soil and a spongy feeling underfoot, similar to freshly laid sod.
Animals like skunks, raccoons and armadillos enjoy eating grubs, which might be beneficial if not for the unsightly holes they leave behind. To reach the grubs, the critters tear through the sod, rooting around in the soil on the hunt for their intended snack. Rather than trapping or killing hungry skunks, raccoons or armadillos, try treating the grubs instead.
Verify the Infestation
If your lawn suffers from one or more of the previously mentioned issues, you can confirm the presence of grubs by inspecting a one-foot section of soil under the grass. The day after a rain or irrigation, cut through the grass on three sides of a one-foot square with a shovel and roll the sod back. You may need to dig down about four inches or so, depending on the variety of grub. Sift through the soil thoroughly and collect, identify and count the grubs you find.
All white grubs look similar with fat, nondescript whitish bodies, making identification difficult. If you’re squeamish, enlist a pro to help you identify and treat the grubs. If you don’t mind handling them, match the grub to the photos below, and closely follow the directions on the appropriate insecticide label.
Green June Beetle
These grubs have tiny legs out of proportion to their overall body size. Examine the soil four inches down. A count of six or eight per square foot warrants treatment. Unlike other grubs, the larvae of Green June beetles emerge from the soil to feed at night, so you may notice small mounds of dirt left behind. This habit also makes them easier to control, since they readily come into contact with the insecticide.
Look for randomly scattered spines on the raster (tail end). The grubs will be found in the top two to three inches of soil, and presence of more than 10 grubs per square foot warrants treatment. Treat after irrigation or rain, and apply another half inch of water after treatment to help ensure the insecticide reaches the grubs.
Sporting a distinct “V” shape in the spines on the raster, these grubs are usually found in the top one to two inches of soil and in the grass roots. Treat after irrigation or rain, and apply another half inch of water after treatment to help ensure the insecticide reaches the grubs.
May or June Beetles
Two distinct parallel rows of spines mark the raster of these grubs. Dig into the soil three to four inches to find and count them. Treat after irrigation or rain, and apply another half inch of water after treatment to help ensure the insecticide reaches the grubs.
If you have questions about damage in your yard, our Certified Turfgrass Professionals are happy to help. Give them a call at 770.832.8608 or email at info@NGTurf.com.