Corn leaf aphid (CLA), is typically an occasional presence in cornfields within the Midwest. They are a common sight late in season, in September and October, when corn is starting to senesce and they can’t have much impact on yields. They are frequently seen on corn stalks close to the ground at this time and can reach very high numbers, with black sooty mold covering some plant parts. Since corn plants are effectively “shutting down” at this time in terms of photosynthesis, they are not a pest of concern at that time.