Lawn Care

Best Armyworm Killers For Lawns (2023)

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By: Mark Marino, a Massachusetts Core Applicator License holder
and owner/operator of Lawn Phix,

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Armyworm on grass blade

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Armyworms are causing devastating damage to crops and lawns in the Tri-State this year.

Armyworms get their names because they travel in groups. As they feed on turf grasses armyworm activity can be spotted from summer to early fall. In years, such as 2021, that see more than average rainfall in August or September, you can expect a higher number of armyworms in the upcoming summer.

With high activity, particularly in untreated lawns, you’ll notice brown patches of grass start out small and grow incredibly fast within a matter of a couple of days. That’s why you need to act fast. Choose one of these armyworm killers and spray according to the labels.

I like Talstar Pro because it’s inexpensive, and at a rate of 1 oz. per gallon, covers many other insects. I also recommend Demand CS due to its low use rate (max of 7 ml per gallon) and quick knockdown. Other options are Talstar granular in combination with Demand SC for both knockdown and preventive coverage on the surface and into the soil.

1. Talstar Pro (Bifen)

Talstar P – Armyworm killer

The best armyworm killer is Talstar Pro, with the active ingredient Bifenthrin. Talstar Pro is labeled for armyworms and over 70 other pests and insects in and around your home. I always keep one gallon of Bifenthrin on hand for the knockdown of surface insects in my lawn, as well as around the foundation of my home to prevent ants. You should see armyworms surface within 15 minutes after spraying. The most preferred killer for armyworms by many professionals. Use 1 oz. per gallon of water with confidence.

2. Demand CS

demand cs insecticide
Demand CS – Armyworm killer

My all-around favorite insecticide. Demand CS has a low use rate of up to 7 ml per gallon, so a little goes a long way. This is my preferred mosquito killer and is also labeled for over 30 other insects and pests. The maker, Syngenta, is one of the most reputable companies on the market that manufactures the ever-popular Tenacity Herbicide, other insecticides like Acelepryn, and fungicides such as Headway G and Heritage G.

3. Permetherin

Permethrin SFR Armyworm killer
Permethrin SFR – Armyworm killer

I love keeping permethrin on hand to mix for ticks. It tank mixes well, especially with Bifen. I also make my own tick tubes with permethrin (soak cotton balls with permethrin and place them inside an empty paper towel roll).

Permethrin is Docs preferred insecticide for armyworm killers. Use 1 2/3 oz. per gallon for a 0.5% solution for armyworm killer.

Armyworm Killers on Amazon

Armyworm FAQs

Does Sevin Kill Armyworms?

Yes, Sevin will kill armyworm. Both products: Sevin Insect Killer by GardenTech (with Zeta-Cypermethrin) and Sevin SL by Bayer (with Carbaryl).

Will grass recover from armyworms?

Healthy turf with strong roots should recover from armyworm damage. But if left untreated, particularly in stressed or weaker grass, fall overseeding and repairs may be needed.

What keeps armyworms away?

A healthy lawn that is treated with an insecticide like Acelepryn will help prevent armyworm damage. Armyworms are actively feeding in the mornings, early evenings, and overnight. During the day they hide from the heat and sunlight under thatch, leaves, and any other shaded areas in your lawn. Rake your lawn of leaves, thatch, debris, and anything that may be a place for armyworms to hide.

What are armyworms?

Armyworms are common turf pests found in the United States that target lawns, crop vegetables, and gardens. They are the larvae of moths and the genus Spodoptera Ornithogalum. Armyworms get their names because they travel in groups as they feed on turfgrasses.

What do armyworms look like?

Armyworms grow to be about 1 – 1.5 inches in length. Their colors are brown, light green, or black bodies. Armyworms are striped lengthwise with recurring lighter and darker stripes on each side. Armyworms have brown to light brown head capsules and their heads often feature a Y shape.

How to check for armyworms in lawn?

To coax armyworms from coming out of your lawn, you can flush them out from hiding by pouring a solution of 1 tablespoon of dishwashing soap and one gallon of water over suspected patches. Pour the one-gallon solution over one square yard at a time and any armyworm should surface within a few minutes.

Does Talstar kill armyworms?

yes, Talstar kills armyworm when applied as directed. Talstar contains the active ingredient Bifenthrin and kills many other pests and surface insects.

How to get rid of armyworms

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Author's Note: this piece has been updated for accuracy since its first publication on
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Author: Mark Marino
I am Mark Marino, the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier services. I am a fully licensed and insured pesticide applicator in Massachusetts, specializing in comprehensive turf nutrition, and weed and pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

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