When should I begin to scout soybean fields in east-central Illinois for western corn rootworm adults?
Throughout east-central Illinois, we recommend that growers determine western corn rootworm densities in soybean fields from the last week in July through the third week in August by using yellow sticky traps (Pherocon AM traps). In the last week of July, distribute 12 unbaited Pherocon AM traps evenly throughout the interior of each soybean field (regardless of field size). The traps should be positioned just above the soybean canopy on metal fence posts. Each week, count all western corn rootworm (male and female) found on each trap in each field. Be sure to replace the traps every 7 days to ensure accurate counts. Producers who are outside the east-central Illinois area and are interested in determining the presence or absence of western corn rootworm adults in soybean fields can follow the same trapping procedures, but use only four traps per field. If adults are detected in soybean fields that have four traps deployed, we recommend the use of 12 traps for a more thorough analysis
