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, โcaterpillars immediately stop feeding, though they may otherwise appear to be unaffected for several days.โ โBt-k degrades quickly in sunlight and โshould be applied โat 5โ-7โ day intervals while they are active. Apply more frequently to control heavy infestations.
Hope it helps!
