Whitish-grey caterpillar with samll black spots on body and shiny black head. From 1/8 - 1 inch long.

Initially feeds on pollen in leaf axil, ear tip, etc. If pollen is not available, borer will move around to sheath and collar area to feed. Later bores into stalk.

Late July, August, and sometimes early September. The larvae overwinter wherever corn is grown.

Look for fields pollinating during early 2nd ECB moth flights. Inspect 10 plants in at least 5 locations, counting egg masses on underside of leaf, and larvae in leaf axils and ear tips.

25 - 50% of plants with an egg mass and corn at blister stage or earlier.

http://www.unl.edu/entomology/extension/crops/fieldcorn.shtml