Relationship of adult European corn borer (Lepidoptera: Pyralidae) in action sites with egg masses in the cornfield.

A relative sampling method for second flight adult European corn borer, Ostrinia nubilalis (Hubner), was used to predict egg mass levels within hybrid seed cornfields ( Zea mays L.). An aluminum bar (1 m) was swept through adult aggregation areas of giant and green foxtail grass ( Setaria spp.) and adults were counted as they flushed from the grass. Numbers of scouted egg masses in the field were regressed onto numbers of flushed adults during early to late silking stages of corn. Egg masses were dependent on the number of European corn borer adults in aggregation areas (example: predicted 0.5 egg masses per corn plant with an average of 52 moths flushed from 10 m2 grass at 5% silking or an average of 66 moths flushed from 10 m2 grass at 80% silking). This relationship between flushed adults and egg masses can be used to determine the need and timing of field scouting by consultants or seed companies for second-generation egg masses in the Corn Belt.