Armyworms Blown In From Florida

Q: We had a bad problem with armyworms in our Bermuda lawn in September. What would you recommend to prevent them, and what process should we follow if they come back? 

A: You can’t get rid of them permanently, since many arrive here riding on storm winds from Florida. Control of the visitors is not hard. Any sprayable lawn insecticide can be applied in a coarse spray over the grass. Wet the grass thoroughly and do not mow for three days after application. Products containing Bacillus thuringiensis (also known as B.t.) are effective only on small (1/2 inch or less) worms. Irrigate before treating to move caterpillars up and out of thatch that has accumulated under the grass. The good news is that armyworms will not hurt a healthy lawn permanently. Fall armyworms rarely kill grass, but some lawns may be severely weakened.