[Doris Miller]

I read your recommendations on treating army worms. I have cattle on the pasture grass being invaded by armyworms. Can the grass be treated where the cows are eating or should we restrict them to one pasture and move them in a couple of days to treat that pasture? Any help would be appreciated. I don’t want to make the cows sick or us later through the beef.

[Eric Vinje]

Hi Doris –

All of the natural pesticides that we recommend on our Armyworm Control page are short-lived in the environment and have less toxicity than commercial chemical sprays. With that said, I recommend using Bacillus thuringiensis (Bt-k) to treat armyworms in pastures. I feel it is the safest, most effective product that you can use for this application.

Harmless to humans, animals and beneficial insects, Bt-k is derived from a naturally occurring soil bacteria. It must be consumed by the caterpillar, as it is a stomach toxin. After ingesting the insecticide, ​caterpillars immediately stop feeding, though they may otherwise appear to be unaffected for several days.​ ​Bt-k degrades quickly in sunlight and ​should be applied ​at 5​-7​ day intervals while they are active. Apply more frequently to control heavy infestations.

Hope it helps!

[Author]

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