Lawn Diseases
Best Grub Killer: Two Actives, and One Aisle Full of Wrong Ones
MSU names six actives that should not be used for grub control at all — and some bags sold as grub killers contain exactly those. Two molecules do the work.
In this guide6 sections
Count first: the threshold
This is the only buying guide on this site whose first recommendation is frequently to buy nothing, and the reason is a number. Penn State’s threshold:
If an average of five grubs per square foot or more is found in non-irrigated turf, or fifteen or more per square foot in an irrigated lawn, an insecticide application may be desirable.
The irrigated figure being three times higher is the important detail. A watered lawn replaces roots faster than the larvae remove them, so the same grub population that ruins a dry lawn is invisible in a maintained one. Which means the honest first step is a trowel, not a bag: cut and fold back a square foot of sod in three or four places across the lawn and count what is underneath.
Our lawn grubs guide covers the counting method and the damage patterns that are actually grubs rather than drought, billbug or dog urine.
The two actives that work
Grub control is not one job. It is two jobs several months apart, and each has its own molecule.
Chlorantraniliprole — the preventive. MSU: most effective applied in May or June. It goes into the soil before the eggs hatch and is still present when the young larvae begin feeding. It also picks up surface feeders — sod webworm and cutworm — as a secondary benefit.
Trichlorfon — the curative. MSU: most effective in late August or early September, against grubs already feeding. This is the emergency option, and it should be bought with realistic expectations, because MSU has measured them:
Curative treatments will kill “20–80% of grubs when applied in September or 20–55% when applied in late October.”
That range is why the preventive route exists at all. MSU’s own framing of the trade-off is worth keeping: the curative approach “avoids unnecessary applications of chemicals, but is not as effective as preventive products.” Both halves of that sentence are true, and which half matters more depends on whether your lawn has a grub history.
Our grub preventer vs grub killer guide works through that decision in more detail.
The actives that do not work
Here is the sentence that should reorganise this aisle. MSU Extension:
Products containing only lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin or permethrin “should not be used for any phase of grub control.”
Those are pyrethroids. They are genuinely effective insecticides — against insects on the surface. They bind tightly to organic matter and thatch and do not move down into the root zone where grubs live, so the grub never meets the chemical.
The problem for a shopper is that the bag does not say this. At least one widely sold product pairs lambda-cyhalothrin with the words Season Long Grub Control on the label. It is not a counterfeit and it is not mislabelled in a regulatory sense — it is simply a surface insecticide sold for a subsurface pest, and it is the reason our own review of it sits below 3 out of 5.
If you take one thing from this page to the shop: turn the bag over and read the active ingredient. If the only active is on MSU’s list, put it back regardless of the name on the front.
The picks
Best preventive — the one to buy in May or June
Scotts GrubEx1 Season Long Grub Killer
★★★★☆ (4.4/5)
true
Best for: Chlorantraniliprole, the active MSU puts in the May–June preventive window, on a lawn with a documented grub history
$18–$24
View on Amazon
Best curative — the one to buy in late August or September
BioAdvanced 24-Hour Grub Killer Plus Ready-To-Spread Granules
★★★★☆ (4.2/5)
The retail trichlorfon product — the active MSU Extension names for CURATIVE grub control, applied late August or early September against grubs already feeding. Its counterpart, chlorantraniliprole, is preventive and belongs in May or June.
Best for: Trichlorfon, the active MSU puts in the curative window, for a lawn already losing turf — with MSU's 20–80% expectation rather than a rescue
$22–$30 (10 lb)
View on AmazonTwo things about that second card are worth reading before you buy it. We read its EPA label (reg. 92564-40) and the registered product name is Dylox 9.3% Insect Granules — the BioAdvanced name is an alternate brand name on the same registration, so the retail bag is Dylox rather than a lookalike. And the label carries a restriction most people would breach without noticing: “Do not apply with hand-held or chest mounted spreader.” On a small lawn that is the applicator many people own, so check what you are spreading it with before ordering.
Named for the job, wrong for the job
BioAdvanced Season Long Grub Control Granules
★★★☆☆ (2.6/5)
The clearest example on this shelf of a product whose name promises a job its chemistry is not the recommended tool for.
Best for: Included here as the example this page is about — lambda-cyhalothrin is on MSU's do-not-use list for grubs, whatever the front of the bag says
$24–$29
View on AmazonBefore you buy, two local checks
Your state may have removed an option. Vermont has prohibited applying neonicotinoid pesticides to turf since July 1, 2025, which takes the imidacloprid and clothianidin season-long products off the table there. That is the sharpest example, but state pesticide rules differ more than most people expect — our state pages carry the local position.
Your species may not be the label’s species. European chafer stays in the root zone later in autumn and returns earlier in spring, which moves the treatment window away from the printed calendar. Oriental beetle, which dominates Connecticut, Rhode Island and coastal Massachusetts, does not answer to every product sold for grubs. Identifying what you dug up is not pedantry here; it changes both the timing and the product.
The honest summary
The best grub killer for most lawns in most years is no grub killer, because most lawns never reach five grubs per square foot and have never been counted. When the count does clear the bar, the month decides the molecule: chlorantraniliprole in May or June if you are preventing, trichlorfon in late August or early September if you are already losing turf. Everything else in the aisle is either the wrong timing or, in the case of the pyrethroid-only products, the wrong chemistry for a pest that lives three inches down.
Common questions
Frequently Asked Questions
What is the best grub killer?
It depends entirely on the month, because two different molecules own two different jobs. Chlorantraniliprole is the preventive, and MSU puts its best window in May or June — it goes down before the eggs hatch and is still there when they do. Trichlorfon is the curative, most effective in late August or early September, for grubs already feeding. There is no single product that does both jobs well, and buying the wrong one for the month you are in is the most common way this purchase fails.
Which grub products should I avoid?
MSU Extension names them outright: products containing only lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin or permethrin 'should not be used for any phase of grub control.' These are pyrethroids — they bind tightly to organic matter at the surface and do not move down to where grubs feed. The awkward part is that at least one product on the shelf carries lambda-cyhalothrin and the words 'Season Long Grub Control' on the same bag.
How many grubs before I treat?
Five per square foot in non-irrigated turf, or fifteen per square foot in an irrigated lawn, is the threshold at which an application 'may be desirable.' The irrigated number is three times higher because a watered lawn grows roots faster than the larvae remove them. Cut and peel back a square foot of sod in three or four places and count. Most lawns that people treat every year have never been counted, and most would not clear the bar.
How well do curative treatments actually work?
Less well than the label implies, and MSU has the numbers: curative treatments kill '20–80% of grubs when applied in September or 20–55% when applied in late October.' That is the honest range for a treatment applied after the damage starts. It is also why the preventive route exists — as MSU frames the trade, the curative approach 'avoids unnecessary applications of chemicals, but is not as effective as preventive products.'
Is preventive or curative the right approach?
Curative if you have never had a grub problem, preventive if you have had one two years running. The logic is that a preventive application is made in May or June against damage that may never come, so on a lawn with no history it is chemistry spent on a guess. On a lawn with a documented history — and in the parts of the country where European chafer or Oriental beetle is established — the preventive window is the one that works, and waiting for damage means accepting the 20–80% figure instead.
Does grub control kill beneficial insects too?
Chlorantraniliprole is relatively low-risk to bees, which is part of why it displaced the neonicotinoids in retail grub products. That displacement is legally mandatory in at least one state: Vermont has prohibited applying neonicotinoid pesticides to turf since July 1, 2025, which removes the imidacloprid and clothianidin season-long products from the shelf there entirely. Check your own state's rule before assuming a nationally sold product is usable.
Do the grubs I found actually matter?
Species matters as much as count. European chafer stays in the root zone later in autumn and returns earlier in spring than the others, which shifts the treatment window off the label calendar. Oriental beetle — the dominant grub across Connecticut, Rhode Island and coastal Massachusetts — does not respond to every product sold for grubs. Identifying what you dug up before buying is a real step, and our state pages name the species that dominates locally.
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Verify our work
📚 Sources & Further Reading
This guide is written against published land-grant university extension research and USDA data. Verify local details with your own state's extension office — and always follow the product label.
- [1]How to Choose and When to Apply Grub Control Products for Your Lawn — Michigan State University Extension(canr.msu.edu)
- [2]White Grubs in Home Lawns — Penn State Extension(extension.psu.edu)
- [3]Managing White Grubs in Turfgrass (E-271) — Purdue Extension Entomology(extension.entm.purdue.edu)
Spotted an error? Tell us — we correct verified mistakes and note the revision date. See our editorial policy.
