Enter your square-foot count and the month — get the treat-or-ignore verdict, the right product window, and the bag math.
The threshold math
<5 per sq ft: ignore · 5–9: water & watch · 10+: treat
preventive window: May–July · curative window: Aug–Sep
Grub control is the most mistimed product in the lawn aisle. The lifecycle is the whole game: beetles lay eggs in midsummer, grubs hatch and feed hard through fall (the damage window), overwinter deep, then feed briefly and pupate in spring. That's why fall counts are honest, curative works in late summer, and spring treatment of fat finishing grubs is theater.
A worked example
6 grubs per square foot in July on a healthy 5,000 sq ft lawn: the verdict is water-and-watch — irrigated turf outgrows this count. The same count on a drought-stressed lawn, or 12+ anywhere: treat now with a curative as August arrives — at a 2.9 lbs/1,000 label rate that's 14.5 lbs. Next May, a preventive application breaks the cycle for the season after.
The bigger picture
Grub damage and drought stress look alike and compound — the brown lawn diagnostic separates them (the peel test is definitive), and a well-watered lawn per the watering schedule tolerates double the grub count of a stressed one. Repair the chewed patches with the overseeding planner once the count is handled.
Frequently asked questions
How many grubs per square foot is too many?
Under 5 per square foot: normal, every lawn has some — ignore. 5–9: a healthy, watered lawn usually outgrows the damage; treat only if the lawn is already stressed. 10+ (or turf peeling up rootless): treatment territory. Count before you buy — most 'grub problems' fail the count.
When should I apply grub control?
Two different products, two different windows. PREVENTIVE (chlorantraniliprole, imidacloprid): late spring through early summer, before eggs hatch — it protects the next generation from ever feeding. CURATIVE (trichlorfon, carbaryl): late summer into early fall, when this year's grubs are small and feeding near the surface. Spring applications against big fat grubs mostly waste money — they're done feeding.
How do I check for grubs?
Where brown meets green, cut three sides of a one-foot square, peel it back, count the white C-shaped larvae in the top few inches, and put the flap back (it usually survives). Do it in 3–4 spots — grub damage is patchy. August and September counts are the most honest.
Do skunks and birds in the lawn mean grubs?
Often — skunks, raccoons, and flocks of starlings tearing at turf are hunting grubs, and their digging frequently outdamages the grubs themselves. It's a strong signal to do the square-foot count, but confirm before treating: they also dig for worms, which you want to keep.