The 2023 moth trapping season is underway, and our volunteers began placing traps the week of March 26. Black cutworm (BCW) monitoring is a long-standing project in Iowa, and true armyworm (TAW) was added in 2017. 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, 31 volunteers established 34 BCW and 34 TAW traps in 26 counties. Volunteers assemble a wing-style trap that is baited with a pheromone lure for each species. Female moths release pheromones to attract males for mating, and a synthetic version 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 injury to the crop is to scout your fields.
Week 1 report:
This past week, Iowa has experienced warm temperatures accompanied by strong, southerly winds, which are ideal conditions for moth flights into the state. The first positive record of moth activity in Iowa occurred on March 31 in Henry County, where 1 BCW moth was reported. Several positive detections of BCW followed during the first week of April, and 3 total TAW moths were reported toward the end of last week. Figures 1 and 2 show where moth traps are established throughout Iowa and where moths were reported during Week 1.
You can track moth flights, black cutworm significant flights, and projected cutting dates for Iowa, Illinois, and Wisconsin at https://corn.ipmpipe.org/insects/. 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 ...