Definition of armyworm
: any of numerous moths whose larvae travel in multitudes from field to field destroying grass, grain, and other crops; especially : the common armyworm (Pseudaletia unipuncta) of the eastern and central United States and Canada
First Known Use of armyworm
Learn More about armyworm
Britannica.com: Encyclopedia article about armyworm
Seen and Heard
What made you want to look up armyworm? Please tell us where you read or heard it (including the quote, if possible).