White grubs are the larvae of June beetles, May Beetles, masked chafers, and several other species of scarab beetles. These insects damage turf grass by pruning roots as they feed on organic matter in the root zone, causing drought stress and poor nutrient uptake. Severe injury can cause grass to die or grow poorly, but in many cases. more damage is caused by predators like armadillos or skunks digging for grubs than by the grubs themselves. Heavy grub infestations are more likely to occur on lawns with high levels of organic matter, lawns that have received heavy applications of organic fertilizer, or lawns with heavy accumulations of thatch. Many species produce one generation per year, but some require more than a year. Low white grub populations occur in most lawns and commercial turf without causing significant damage. If you suspect a white grub infestation, use a knife to cut one to two square foot sections of turf, roll it back, and look for grubs in the top two to three inches of soil. For larger species like June beetles and May beetles, treatment is recommended if populations exceed three to five grubs per square foot. The best time to check for white grubs is in late fall or spring, when grubs are larger and easier to spot.
Control: The best time to treat for white grubs is in June to early July, when grubs are small and more easily controlled. This is when grub damage is least obvious, but treating at this time can prevent future damage. Apply products containing clothianidin, chlorantraniliprole, imidacloprid, or halofenozide and water-in according to label directions. These treatments work best against young recently hatched larvae. Use treatments containing trichlorfon or carbaryl if it is necessary to control heavy infestations of older grubs during the spring.
See page 7 of Control Insect Pests In and Around the Home Lawn, for more information on white grub control.
For recommendations for white grub control in commercial turf see page 9 of Insect Control in Commercial Turf.
Let others know about the Bug’s Eye View Newsletter: If you know someone who might enjoy receiving the Bug’s Eye View Newsletter, please share. They can easily subscribe by clicking on the sign up link shown below.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.