All species of grubworms typically have one generation per year except the black turfgrass Ataenius may have two per year. Most species live through the winter in the thatch or soil as larvae in the third instar grubworm stage. An exception is the Black Turfgrass Ataenius, which lives through the winter as an adult beetle.

Over-wintering grubworms will move up to feed in the spring and then move down into the soil to pupate. Adult beetles emerge, mate and lay eggs. First instar grubworms hatch and begin feeding before the molting process begins. The seasonal timing of the complex metamorphosis life cycle varies with each species.

The larvae white grubworm live below the soil surface and feed on the roots of the turfgrass. Turf damage consists of wilted, dying or dead patches of turf. Damage to the turf can also occur from birds, skunks and moles digging for grubworms.

Adult beetles are commonly seen in flight around lights in the evening. Signs of predator damage digging for grubworms is a valid signal of larvae presence. Grubworm damage severs the root structure, allowing one to easily pull up or roll back dead sod. Doing this often exposes grubworms curled up in a C-position. The various species of grubworms can be identified by the pattern of spines on the raster. Their raster is the underside of the tip of their abdomen, which is at the end of the grubworm.

Generally population levels of 5 to 10 grubs per square foot in poorly irrigated turf or 15 to 20 grubs per square foot in properly irrigated lawns will need control measures to minimize damage. Insecticides are most effective when the larvae have just hatched and are their first instar. The more mature the grub the more difficult it is to control. It is very important to water the insecticide treatment down into the soil.

Contact us if these bugs are causing you a problem, and discuss which insecticides would be most effective for controlling these lawn pests.