2024 Iowa Moth Trapping Network Update: Week 1

April 10, 2024 11:14 AM
Blog Post

The 2024 moth trapping season is underway, and our volunteers began placing traps the week of March 24. Black cutworm (BCW) monitoring is a long-standing project in Iowa to detect moths migrating from southern overwintering sites each spring. By monitoring adult black cutworms, we can provide scouting recommendations to growers to avoid significant injury from black cutworm larvae.

black cutworm moth and larva Adam Sisson
Photo 1. Left: black cutworm moth. Right: black cutworm larva. Photos by Adam Sisson.

Because populations are unpredictable, we ask for volunteers around Iowa to set up traps to monitor BCW flights in Iowa. This year, 25 volunteers established 31 BCW traps in 22 counties. Volunteers assemble a wing-style trap that is baited with a pheromone lure. Female moths release pheromones to attract males for mating, and a synthetic version of the pheromone is used for the lures in our traps. Unsuspecting males fly into the trap and are caught in the sticky substance at the bottom.

black cutworm moths stuck in a trap
Photo 2. Black cutworm moths caught in a wing-style pheromone trap.

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. Since this pest is erratic, the best way to know if BCW is causing injury to the crop is to scout your fields.

Week 1 report:

The first positive record of moth activity in Iowa this year occurred on March 24 in Muscatine County, where 1 BCW moth was reported. Several positive detections of BCW occurred at that site the following week, and 2 moths were reported in Buena Vista County as well. Volunteers reported a total of 5 BCW moths during the first few weeks after traps were placed. Figure 1 shows where BCW traps are established throughout Iowa and where moths were reported during Week 1.

BCW reports 2024 Week 1
Figure 1. Black cutworm moth captures from March 24 to April 6. The bold number indicates the total moth count for the week (for counties with multiple sites, only the site with the highest weekly moth count is reported; highlighted counties without numbers indicate that traps are placed but no reports have been received). Data is current as of April 10, 2024.

You can track black cutworm captures, significant flights, and projected cutting dates for Iowa, Illinois, and Wisconsin at https://corn.ipmpipe.org/insects/. At the time of publication of this blog post, some of the BCW data on this website is out of date, but we will get it updated soon! Although we are not monitoring true armyworm (TAW) in Iowa this year, you can see data from other states on the website as well.

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 ...