GrubEx does not kill ants. Its active ingredient, chlorantraniliprole at a concentration of 0.08%, targets beetle larvae (grubs) living in soil. It is not labeled for ant control and will not eliminate ant colonies in your lawn, even if individual ants happen to contact treated soil.
What GrubEx Actually Targets
GrubEx is a preventive product designed to kill white grubs, the larval stage of beetles like Japanese beetles and European chafers. These C-shaped larvae feed on grass roots underground, causing brown patches that peel up like loose carpet. Chlorantraniliprole works by disrupting muscle function specifically in this group of insects, and it needs to be applied before grubs are actively feeding, typically in spring or early summer.
The product’s narrow target range is a feature, not a limitation. Chlorantraniliprole is not very toxic to earthworms and, when applied according to the label, generally does not harm beneficial predatory insects. That selectivity is also why it has little to no effect on ants. The chemical simply does not work through the pathways needed to destroy an ant colony.
Why GrubEx Won’t Work on Ants
Even if chlorantraniliprole killed a few foraging ants on contact, that would do almost nothing to solve an ant problem. Ant colonies can contain thousands to hundreds of thousands of workers, and the queen (or queens) producing new ants lives deep underground. Killing surface workers without reaching the queen is like bailing water from a boat without plugging the hole. The colony replaces lost workers within days.
Effective ant control requires products that either penetrate deep into the nest or, better yet, get carried back to the queen by foraging workers. GrubEx does neither. It sits in the top layer of soil waiting for grubs to ingest it. Ants walk right over it.
What Actually Kills Lawn Ants
Ant control products fall into two broad categories: baits and contact insecticides. Each works differently, and the right choice depends on how fast you need results and how permanent you want the solution to be.
Baits
Baits are the most effective long-term solution because worker ants carry the poison back to the colony and feed it to the queen. Once the queen dies, the colony collapses. Common bait active ingredients for lawn ants include hydramethylnon, indoxacarb, spinosad, and methoprene (which is a growth regulator that prevents larvae from maturing). Baits work slowly, often taking one to several weeks to eliminate a colony, but they address the root of the problem rather than just the visible ants.
Contact Insecticides
Granular or liquid products containing bifenthrin or lambda-cyhalothrin kill ants on contact and work quickly. The tradeoff: they typically only control ants on the surface and do not eliminate colonies nesting deeper in the soil. You may see fast results, but the colony can rebuild if the queen survives. For fire ants specifically, fipronil is a slow-acting option that provides longer-lasting control, though it is generally limited to one application per year.
For small ant mounds scattered across a lawn, broadcasting a bait product over the entire yard tends to work better than treating individual mounds. For a few large, clearly defined mounds, you can treat each one directly with a contact insecticide or a mound drench. Combining a broadcast bait with individual mound treatments gives you both speed and lasting control.
Can You Use GrubEx and Ant Products Together?
If you have both a grub problem and an ant problem, you can treat for each separately. GrubEx is typically applied in spring, and most ant bait products can be spread at a different time without interference. Just avoid applying them on the same day to the same area, since granular ant baits need to stay dry and accessible to foraging ants, and watering in GrubEx (which the label requires) could wash away or dilute a bait applied at the same time. Space the applications out by at least a few days and water in only the product that calls for it.