Although a large saltmarsh caterpillar can eat an entire cotton leaf in an amazingly short period of time, larvae are rarely numerous enough to require treatment. Occasionally, scouts may find a dead or dying saltmarsh caterpillar that is stuck to the leaf in a mass of white, cottony webbing. This is a caterpillar that has been parasitized by a small wasp whose larvae emerge from the caterpillar before spinning a group cocoon. One of the most distinguishing characteristics of this moth is the triagular, jet-like shape in which it holds its wings when resting. The wings are a creamy yellow to yellowish brown in color and are crossed by a couple of wavy brown lines.
ECB moths are smaller than bollworm moths and slightly larger than beet armyworms.
ECB is primarily a pest of corn and sorghum, and these are the crops from which these moths are migrating. They will also attack cotton, but, because they are susceptible to many of the insecticides used in cotton, it is uncommon to find ECB larvae in cotton. They are usually controlled coincidentally by treatments targeting other pests. When they do occur, it is usually in fields that have not required treatment for an extended period of time or as a result of larvae hatching from eggs that were deposited in between insecticide treatments for other pests. ECB is susceptible to Bt and therefore is not likely to be a problem in Bt-cotton.