Identification of white grubs and treatment at the correct time in their life cycle is key for their control.
White grubs are thelarvae of Japanese beetles, June beetles, or masked chafer beetles.
They cause damage to lawns by feeding on the roots of grass.
Credit: Jay Wilde
Identifying the Pest
Depending on the species, grubs may have a one-year to three-year life cycle.
Annual white grubsare the larvae of the Japanese beetle, masked chafer beetle, and others.
When to Control Grubs
Controls are most effective on immature grubs.
Check out the seasonal lawn-care schedules for theNortheast,Midwest,Pacific Northwest, andSouthern California.
The downside is that milky spore usually takes several years to take effect.
Furthermore, it requires some grubs to live on, so don’t use it together with chemical controls.
Milky spore comes in powder form and it is only effective on Japanese beetle grubs.
Nematodes
Beneficial nematodes are microscopic worms that live in the soil.
They seek out grubs, and after entering their bodies, release bacteria that act as killers.
The two major types of insect parasitic nematodes areSteinernemaspp.
These two types of nematodes are effective on all types of grubs.
Weather and Irrigation
Grub populations are usually the highest when soil conditions are consistently moist.
This strategy may work well for bluegrass lawns, which recover well from summer dormancy.
But if your lawn is consistently attacked by grubs, you might want to consider applying a chemical insecticide.
Chemicals labeled for curative control are carbaryl, halofenozide, and imidacloprid.
Water in the chemical controls how they penetrate the soil and act on the grubs.
Most insecticides not only kill white grubs but they are also highly toxic to bees and other pollinating insects.
