"They are here to stay," Professor Lynn Robbins of Missouri State University tells the St. Louis Post-Dispatch.
The football-size creatures feast on beetles, grubs and earthworms. It is said they can smell insects through 6 inches of soil.
Prolific diggers, their handiwork has left some yards looking as if a "plow had gone through," says Tom Meister, a wildlife damage biologist for the Missouri Department of Conservation in the St. Louis area.
Because the armadillo is a non-native species, there are few restrictions preventing Missouri property owners from shooting or trapping armadillos suspected of causing damage -- although it rarely goes that far, Meister says.
The armadillo was, over some resistance, made the state small mammal of Texas, where it is considered a pest.