Nature's Armyworm Control System
If your yard has good diversity of plants, you feed songbirds, and you don't use any broad spectrum insecticides the following beneficial insects and songbirds love to eat aphids and if in sufficient numbers will keep armyworms under control.
Beneficial insect predators - Assassin Bugs, Bigeyed Bugs, Ground or Tiger Beetles,Rove Beetles, Spiders, and Tachinid Flies eat armyworms for lunch.
Songbird predators - Robins and Starlings love armyworms.
If you don't have this army of predators on your property, the rest of this file will help you deal with your armyworm problem.