Grub Lifecycle

• In June or July, beetles and chafers lay eggs in your lawn's soil just before dying. The eggs will hatch in about two weeks into grub larvae. The grubs start to eat the grass roots. An adult grub is about 1 to 1-1/2 inches long depending on the species. In fall as the soil temperature drops, the grubs move deeper in the ground. The grub re-emerges in spring when the soil temperature warms.
  
  The grub larvae goes into the pupa stage and emerges from the ground as an adult beetle or chafer, which will fly around, mate and lay eggs before dying. Some beetle grub larvae live in the ground for up to three years, but this depends on the species.
  
  

Checking For Grubs

• Pull back a 1-square-foot section of the brown grass 3 inches deep. If you see 10 or more C-shaped white worm-like bugs in that patch, you have grubs that have eaten the grass roots. Check one or two more brown patches. If you find the grubs, you have a population of grubs that needs to be treated or they will continue to kill your entire lawn.
  
  

Holes in Your Lawn

• During late summer and fall, if you have holes about 1-inch in diameter and 3 inches deep, you have predators digging for grubs. Skunks and raccoons will dig holes in the lawns to feed on the grub larvae. Although the predators eat the invasive grub, you still must treat your lawn. Predators don't eat all of the grubs.
  
  

Grub Treatment

• Milky spore disease or nematodes have been successful in controlling the grub population, but both of these biological methods do take some time to work. Milky spore disease is applied to the lawn in powder form. After watering, the disease soaks into the soil where the grubs eat it. After the grub dies, it explodes and releases more milky spore disease.
  
  Nematodes are microscopic parasites. The ground is watered before and after the nematode parasite is released into the soil. The nematodes enter the grub, where they multiply and kill the grub. When the grub dies, more nematodes are released. Both of these methods are long term and will continue killing grubs for years.