As known to have a fall presence, the armyworm is a caterpillar of a gray moth at about 1.5" inches in length. It's known to maintain a hairy body with colors of brown, green and black with a black head. It's also easy to notice a light yellow and white hair line from front to back with a dark line on both sides.
The armyworms most common problem gives into lawns. While traveling in large groups they find most well eating times in dark nights. While making bare lawn and round shapes to grass they eat it down to the soil. Many times their damage looks a lot like what you would see from sod webworms. When you lift damaged sod you will find armyworms in the soil.
The best controlling method is to spray the infested grass or plants with Bacillus thuringiensis (or Bt), known in detail from Wikipedia. The best time to spray is 10 to 14 days until the armyworms are controlled and re-apply after a rain fall.
As seen in spring, moths in the armyworm team lay eggs which develop into caterpillars late summer and fall. Similar to Northern states, a generation is usually once a year, where Southern states experience four to five.
Another known method is to keep a variety of songbirds, chipmunks and toads to make an effort for your advantage to armyworm existence.