[header] How to control armyworms [title] Look for early signs. [step] Because they feed at night, you may not see the caterpillars right away. Brown spots on your lawn are often the first sign that you have an armyworm problem. 
An increase of the number of birds in your yard may be an indication of armyworms. The earlier you treat the problem, the easier it is to control and less damage a lawn will sustain.