Grub killer: the options compared
Timing decides which grub killer works. Preventives (chlorantraniliprole, as in GrubEx, and the neonicotinoids such as imidacloprid) go on before the eggs hatch in midsummer and kill the grubs as they hatch. Curatives, above all trichlorfon, go on in late summer after a count finds grubs, while they are still small. By spring, grubs are large and hard to kill. Of the biologicals, the nematode Heterorhabditis bacteriophora has the most field evidence but is inconsistent. Milky spore and Bt galleriae have failed in university trials. Count first: most lawns need nothing in a given year.
Also sold or listed as: grub control, lawn grub treatment.
At a glance
- Active
- Nematodes, milky spore, Bt galleriae and soil insecticides compared
The options side by side
- Count first, and often do nothingThe best first step for most lawns. Kentucky Extension says only a small share of lawns needs treatment in any given year, and irrigated turf can sometimes carry 20 or more grubs per square foot without damage. Sample in August and treat only above the threshold for your species.
- Chlorantraniliprole (preventive, e.g. GrubEx)The preventive to choose if you treat before you know. It goes on early, from April into early summer, and the label claims up to four months' control from its one application a year. Minnesota Extension rates it effective and low risk for bees, and UMass says it has no activity against bees, ants or wasps. Purdue lists it for preventive and early curative use, not as a late rescue.
- Imidacloprid and other neonicotinoids (preventive)Reliable when timed before egg hatch: 83–100% control of young Japanese beetle grubs in Tennessee nursery trials. Kentucky Extension says imidacloprid is not very effective on older grubs, so it is not a late-summer rescue. Purdue's 2023 table lists all three neonicotinoids, imidacloprid included, for curative use as well, which conflicts with Kentucky's older advice. Its drawback is pollinators: mow out flowering weeds first.
- Trichlorfon (curative, e.g. Dylox)The fast rescue once a count finds grubs. UMass says it kills what it will within one to three days and breaks down within 7–10 days. Timing still matters: against full-grown grubs in mid-September, curative sprays seldom give more than 50% control. Toxic to bees, fish and birds.
- Carbaryl (e.g. Sevin)The weakest of the chemical options. UMass calls it very inconsistent, sometimes leaving more grubs in treated plots than untreated ones. Minnesota still lists it among effective curatives, and Purdue lists it for early and late curative use. Very toxic to bees.
- Grub nematode, Heterorhabditis bacteriophoraThe biological option with the most field evidence, but inconsistent. Apply in late summer to moist soil that will stay above about 12 °C for two weeks, and water it in at once. Kentucky Extension finds it much less reliable than conventional insecticides, and Penn State notes that most researchers find Heterorhabditis usually beats Steinernema against grubs.
- Milky sporeSkip it. It infects Japanese beetle grubs only, and does nothing to chafers or May/June beetles. In Kentucky trials it failed even against Japanese beetle, and Minnesota Extension says modern trials show no benefit. Penn State says it may take three to five years to establish.
- Bt galleriae (grubGONE!)A gamble. The granules failed against Japanese beetle grubs at several field sites in a University of Kentucky-led study. Purdue cites 35–100% control depending on the grub species, and Minnesota calls results inconsistent. Its leaf spray for adult beetles has better evidence than the grub product.
What it works on
- White grubs in lawnsMasked chafers, Japanese beetle, European chafer, Oriental beetle and May/June beetles. Their thresholds differ, and milky spore affects only one of them.
- Japanese beetle grubsMinnesota Extension says controlling the grubs is unlikely to reduce the number of adults on your plants, because beetles fly in from elsewhere.
- May/June beetle grubsA two- to three-year cycle (Kentucky Extension). Milky spore does nothing to them.
How it works
Most lawn grubs have a one-year cycle. The beetles lay eggs in the lawn from late June to early August, the eggs hatch in about two weeks, and the young grubs feed near the surface through August and September. That leaves two windows. A preventive product goes on before the eggs hatch and has to last in the soil until they do; Kentucky Extension gives mid-May through July. A curative product goes on after a count confirms grubs, ideally from late July to early August while they are small. Most curatives last two to three weeks or less, so they must be timed to when the grubs are there. Kentucky Extension calls spring a poor time for curative treatment: overwintered grubs are large and hard to kill, and the lawn usually outgrows the damage before they pupate.
The choice is a trade. Preventives are easier to time, but you have to decide before you know whether you have a problem, and only a small share of lawns needs treatment in any year. Curatives treat only lawns that need it, but miss the window and they fail: once grubs are full-grown, often by mid-September, UMass says curative sprays seldom give more than a 50% reduction. Kentucky Extension says no biological product gives reliable control of white grubs. In Tennessee nursery trials, imidacloprid applied from May to July gave 83–100% control of young Japanese beetle grubs, against 0–75% from biological treatments.
Using it
- Count first
- In August, cut out a square foot of turf in several places and count the grubs in the top 2 inches. Treat above about 5–10 per square foot, depending on the species. See white grubs.
- Preventive window
- Chlorantraniliprole: GrubEx's label allows early April to early August; UMass advises mid-April to early June. Imidacloprid: mid-June to mid-July is best, per Kentucky; Purdue says early to mid-July is almost always best for preventives. UMass says no earlier than mid-June in New England.
- Curative window
- Late July to mid-September (Minnesota); August or early September (Kentucky). The Dylox trichlorfon label says July to September, while grubs are young and feeding near the surface.
- Rates on two home labels
- Scotts GrubEx (0.08% chlorantraniliprole): 2.87 lb per 1,000 sq ft, once a year. Dylox 9.3% granules (trichlorfon): 2 lb per 1,000 sq ft, at most 3 times a year and not within 7 days of the last.
- Water it in
- Kentucky: ½–1 inch of water straight after treatment, to carry the insecticide to the roots and draw the grubs up. GrubEx: about 1 inch. Dylox: within 24 hours. Nematodes: at once.
- Before you treat
- Mow and rake out thatch. In thatchy turf most of the insecticide binds to the organic matter and never reaches the grubs; Kentucky suggests dethatching first if the layer is more than ½ inch thick.
- Hard water
- Trichlorfon and carbaryl break down quickly in water above pH 7.2. With alkaline water, add a buffer (UMass).
Cautions
- Bees
- Minnesota Extension: trichlorfon, clothianidin and carbaryl are all toxic to bees, and imidacloprid and clothianidin products pose a hazard to pollinators. Mow flowering weeds such as clover just before or right after treating, and avoid areas used by ground-nesting bees. Chlorantraniliprole is the low-risk choice for bees.
- Water and wildlife
- The Dylox label calls trichlorfon toxic to fish, birds and wildlife, and bars use near ponds, streams or lakes. The GrubEx label calls chlorantraniliprole toxic to aquatic invertebrates and carries a groundwater advisory for permeable soils.
- Children and pets
- Keep them off until the product has been watered in and the grass has dried (Dylox and GrubEx labels).
- Moles
- Killing grubs will not stop moles, which also eat earthworms. It may discourage skunks and raccoons from digging (Kentucky).
Use instead
- Leave light infestations alone: healthy turf outgrows a few grubs per square foot
- Avoid frequent watering in June and July, which draws egg-laying beetles; water deeply in late August and September to carry the lawn through
- Renovate badly damaged bluegrass or ryegrass with tall fescue, which Kentucky Extension says tolerates grubs better
- Protecting roses from Japanese beetles is a separate job: see Japanese beetle
Other products
Sources
Univ. of Kentucky ENT-10, Controlling White Grubs in Turfgrass (M.F. & D.A. Potter, 1999)
Purdue Extension E-271, Managing White Grubs in Turfgrass (Richmond, 2023)
Penn State Extension, White Grubs in Home Lawns (Heller)
Univ. of Minnesota Extension, Japanese beetles in yards and gardens (reviewed 2025)
UMass Extension, Current Insecticide Approaches for White Grub Control (Vittum, rev. 2013)
EPA label, GrubEx III / GrubEx 1 (Scotts), chlorantraniliprole 0.08%, Reg. 538-306
EPA label, Dylox 9.3% Insect Granules (BioAdvanced), trichlorfon, Reg. 92564-40
EPA label, IMI 1.47% Concentrate (Bonide), Reg. 53883-205 (2019)
Mannion et al., Management of early-instar Japanese beetle, J. Econ. Entomol. 94:1151–61 (2001)
Redmond et al., Btg SDS-502 against Japanese beetle, Pest Manag Sci (2020)
Redmond & Potter, Lack of efficacy of Bacillus popilliae, J. Econ. Entomol. 88:846 (1995)
Drafted from the cited sources, then checked claim by claim against those sources on 23 September 2026.
Always follow the label. Labels are legally binding; this page is not.