With the late flight of the beetles, we do not anticipate damage to occur until late August in southern Illinois and until almost mid-September in northern Illinois. Grub numbers of ten or more per square foot are likely to cause turf damage. If raccoons, skunks, or birds feed in the area, turf damage will occur at much lower numbersthree to five grubs per square foot. Skunks tear out divots of turf that are three to six inches in diameter. While a raccoon usually tears out six or fewer sections of turf in an area, a skunk usually makes 30 or more holes.
Birds pick at the turf, tearing out the sod in one-inch pieces.
Such feeding causes the affected areas to turn brown from the removed thatch and sod. Triumph is labeled for use only on home lawns, sod farms, and golf course tees, greens, and aprons. Diazinon is not labeled for use on golf courses or sod farms. Grubs treated with diazinon will stop feeding but will take about three weeks to die.