How to Spot and Stop Grubs in North Shore Lawns
How to recognize grub damage in North Shore lawns, when grubs are active in Illinois, and the treatment timing that actually works.
If patches of your lawn suddenly turn brown in late summer and the grass pulls up like a loose carpet, you probably have grubs. They are one of the most common lawn problems we see across the North Shore, and they do their worst damage right when your lawn should look its best.
What grubs are
Grubs are the larvae of beetles, including the Japanese beetles that show up on our roses and lindens every summer. They live in the soil and feed on grass roots. Because they cut the roots, the damaged turf lifts away easily, and that peel up test is the fastest way to confirm them.
Signs to watch for
- Irregular brown patches that appear in late July through September.
- Turf that rolls or lifts back like sod with almost no root holding it down.
- Spongy feeling areas underfoot before the browning even starts.
- Skunks, raccoons, or birds digging up the lawn, since they are hunting the grubs.
How many is too many
Cut a one foot square flap of turf and fold it back. Under five grubs per square foot, a healthy lawn shrugs it off and no treatment is warranted. Six to nine is borderline and depends on how stressed the lawn already is. Ten or more per square foot is where you see real damage and treatment makes sense.
Timing is the whole game
A few grubs in a healthy lawn is normal and nothing to panic about. It is when the population climbs that the damage gets serious. Prevention and treatment target different stages of the beetle life cycle here in Illinois, so applying at the wrong time wastes money and does very little.
Preventive products go down in June through early July, ahead of egg hatch, and they are the more reliable approach. Curative products target grubs already feeding and work best in late August and early September while the larvae are still small and near the surface. By October the grubs have burrowed deep to overwinter and nothing reaches them.
Repair comes after
If you are seeing brown patches you cannot explain, have someone look before you reseed, because reseeding over an active grub problem just feeds them. Once the grubs are handled, the dead areas need raking out and overseeding, and early fall happens to be the ideal moment for exactly that.
Related readingHow to repair the damage once grubs are handledNot sure whether you are looking at grubs, drought, or disease? Call or text 224-634-0673 or 224-200-8363 and we will help you sort out what is actually going on.
Frequently asked questions
- How do I know if I have grubs in my lawn?
- Pull on a brown patch. If the turf lifts away like loose carpet with almost no roots attached, grubs have severed them. Cut a one foot square and fold it back to count. Ten or more grubs per square foot warrants treatment.
- When should I treat for grubs in Illinois?
- Preventive products are applied in June through early July, before eggs hatch, and are the most reliable option. Curative treatments work on active grubs in late August and early September. October applications rarely work because the grubs have burrowed deep.
- Why are skunks digging up my lawn?
- They are hunting grubs. Skunks, raccoons and birds tearing up sections of turf is one of the earliest reliable signs of a grub population large enough to be worth treating.
- Can I reseed a lawn damaged by grubs?
- Yes, but confirm the grubs are handled first. Seeding over an active infestation simply provides fresh roots for the larvae to eat. Treat, rake out the dead turf, then overseed, ideally in the early fall window.
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Ruiz Landscaping serves Vernon Hills, Libertyville, Mundelein, Buffalo Grove, Lincolnshire, Long Grove and the rest of Vernon Hills's surrounding North Shore and Lake County communities.