Moth trapping update #2

This week we begin Week 7 of moth trapping in Iowa. Significant captures of black cutworm (BCW) have occurred in several counties during weeks 3-6 of trapping (bold and * in Table 1). Significant captures occur when 8 or more BCW moths are caught in a wing-style pheromone trap over 2 nights. Another type of trap used to monitor BCW activity is a bucket trap. This type of trap tends to capture more moths, but determinations about significant flights are not made in our table because a reliable threshold does not exist yet.

Trapping data for BCW are used to estimate cutting dates for corn when significant flights are reported. Since significant flights have occurred in some areas, estimated cutting dates were posted on ICM News. No thresholds exist for true armyworm (TAW) to predict their activity in fields. We continue to monitor TAW (Table 2) to detect when they are present in a particular area and help guide scouting activities for farmers.

Surrounding states also monitor and report findings of BCW and TAW. If you are near the state borders, it may be beneficial to check these resources periodically. Some state resources are listed below, but others may be available online soon:

• University of Minnesota: https://swroc.cfans.umn.edu/agricultural-programs/pest-management/black-cutworm-reporting-network
• University of Missouri: https://ipm.missouri.edu/pestMonitoring/
• Purdue University: https://extension.entm.purdue.edu/newsletters/pestandcrop/article/2019-black-cutworm-pheromone-trap-report/