The 2022 moth trapping season is underway, and most of our volunteers placed traps the week of March 27. Black cutworm (BCW) monitoring is a long-standing project in Iowa, and true armyworm (TAW) was added in 2017 (Photo 1). Both of these pests are migratory, making it difficult to predict where populations will establish year to year.
Because populations are unpredictable, we ask for volunteers around Iowa to set up traps to monitor BCW and TAW flights in Iowa. This year, 44 volunteers established 46 BCW and 45 TAW traps in 32 counties. Volunteers assemble a wing-style trap (Photo 2) that is baited with a pheromone lure for each species. Female moths release pheromones to attract males for mating, and synthetic versions of the pheromones are used for the lures in our traps. Unsuspecting males fly into the trap and are caught in the sticky substance at the bottom.
These efforts allow us to refine pest movement into the state and estimate scouting and treatment windows for farmers based on significant flights of BCW. A significant flight of BCW occurs when 8 or more moths are captured in a pheromone trap over two nights. No such threshold exists for TAW, but monitoring allows us to inform farmers in the area and support scouting activities. Since these pests are erratic, the best way to know if BCW or TAW are causing damage to the crop is to scout your fields.
Week 1 report:
Temperatures across Iowa have been too cold for much insect activity, so it's not surprising we did not have many reports of moth captures during the first week. The first positive record of moth activity in Iowa occurred on March 31 in Taylor County, where 1 BCW moth was reported. This was the only positive record during the first week of moth trapping. Figures 1 and 2 show where moth traps are established throughout Iowa and where moths were reported during Week 1.
Surrounding states also monitor and report BCW and TAW captures. If you live near the state border, it may be beneficial to check these resources periodically. More resources may be available than what is listed here:
Ashley Dean Agriculture and Natural Resources Extension Specialist II
Ashley is an education extension specialist for field crop entomology at Iowa State University. She coordinates the Iowa Moth Trapping Network, the Regional Corn Rootworm Monitoring Network, and the Iowa Pest Alert Network. She also develops educational resources for field crop pests in Iowa and ...