Checking for Grubs

• Before choosing an insecticide for grub control, it is important to determine the extent of the problem. Cut a 6-inch by 6-inch square of turf with a flat spade, recommends the University of Rhode Island. More than three grubs present in the sample constitutes a significant infestation. The best time to take a sample is in the late summer or early fall when grubs become active.
  
  

Choosing Insecticides

• Different types of insecticides can effectively control grubs, but over time, grubs may become resistant to a particular chemical. Contact a nursery to help find the best grub insecticide for your area. Some chemicals recommended by the University of Kentucky include trichlorfon, carbaryl, clothianidin, halofenozide and chloranthaniliprole.
  
  

Seasonal Applications

• Apply insecticides in the autumn when grubs are actively growing, suggests the University of Rhode Island.