Grubs are the lawn-destroying larvae of several types of beetles, including June beetles and Japanese beetles. Despite the different beetles involved, mature grubs look very similar. Their semi-transparent, grayish-white bodies measure slightly more than 1 inch long. When disturbed, grubs curl into a "C" shape similar to cutworms, but usually not as tight.
Though grubs look a lot like billbug larvae, which also damage lawns, they're easy to tell apart. Billbug larvae don't have legs, but grubs have three pairs right behind their brownish heads. Grubs don't have any fleshy false legs, like caterpillars do.
Grub damage usually shows up in late summer and early fall as lawn grasses wilt and start to turn brown. By this time, grubs that hatched in early summer have been feeding on grass roots for months. Sunny, well-irrigated lawns sustain the worst grub-related damage.
Grub-damaged turf feels soft and spongy underfoot, almost as though it's not attached. That's for good reason. During heavy infestations, cutting the turf into a 12-inch square and rolling it back like a carpet can reveal the extent of the damage. Five grubs in a 12- inch square signals a problem. Ten or more means the infestation is severe.
Grub control is most effective when treatment coincides when grubs are closest to the lawn surface. Late summer and fall treatments target these pests when they're still small, before they go deeper into the soil for the winter months. Early spring treatment catches them as they start to feed again. To reduce grubs in the future, treat for grubs and treat adult beetles before they can reproduce. Amdro® products fight these pests at both life stages:
Heavy thatch in your lawn works like a layer of protection for root-feeding grubs. For maximum impact, mow your lawn lower than normal and dethatch, if needed, before you treat for grubs.
Always read product labels and follow the instructions carefully, including application rates.
Amdro and Amdro Quick Kill are registered trademarks of Central Garden & Pet Company.
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