Some growers use pheromone traps to monitor the population. If your traps catch 20 to 30 moths a night for 3 to 5 nights in a row, begin your weekly checks.


Check high-risk areas first if you are a high-volume grower. Check late-planted corn, fields that are flowering or have young pots, and those growing on elevated areas of the land. Corn grown on elevated areas or knolls is more vulnerable to egg laying.;
, They lay eggs on the silk attached to the husks, which gives larvae easy access to the ears.
 If you are growing several acres of corn, take at least 1 sample per 4 acres. If you are simply checking a home garden, only 1 sample is necessary.
 A 3-foot-long cloth allows you to sample 6 row feet if you check the plants on both sides.
, Check the sheet to see how many worms are on it are at least 3/8-inches long. Worms smaller than that can not do plant damage and may not survive long enough to be a problem.
 If you used a 6-foot-row sample, you would divide the number of worms by 6. Your tolerance threshold is determined by row foot count and varies with the specific crop and the percentage of it under attack.


If you are growing a small amount of corn for your own consumption even one per plant may be too many. Many large production growers usually have a higher threshold.
Check your corn plants for earworms weekly when moth activity in your area has peaked.
Keep an eye on the silk when it forms to see how many eggs the earworms lay.
Pick an area to check in several different spots throughout your fields.
Lay a cloth or sheet of flexible material on the ground between 2 rows of corn.
Bend each bordering plant over the sheet and beat it vigorously with your hand or a small stick.

,
Count the number of earworms.
Determine the number of earworms per row foot.
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