2022 Iowa Moth Trapping Network Update: Week 1

April 7, 2022 3:08 PM
Blog Post

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.

black cutworm and true armyworm
Photo 1. Top left: black cutworm moth. Bottom left: black cutworm larvae. Top right: true armyworm moth. Bottom right: true armyworm larvae.

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.

armyworms stuck in a wing-style trap
Photo 2. Armyworm 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. 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.

TAW reports March 27 to April 1
Figure 1. True armyworm moth captures from March 27 to April 1. The total moth count for the time period is noted on the map for each county; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 5, 2022.

BCW reports March 27 to April 1
Figure 2. Black cutworm moth captures from March 27 to April 1. The total moth count for the time period is noted on the map for each county; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 5, 2022.

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:

Author: 

Ashley Dean Education Extension Specialist I

Ashley is an education extension specialist for field crop entomology at Iowa State University. She coordinates the Iowa Moth Trapping Network, develops educational resources for field crop pests in Iowa, and aids in the research efforts of the