Iowa Moth Trapping Network Update: Weeks 1 and 2

April 24, 2020 9:24 AM
Blog Post

Moth trapping in Iowa is underway. Each year, we monitor field crop pests to help inform scouting activities in Iowa. In 2020, our moth trapping network includes black cutworm (BCW) and true armyworm (TAW; Figure 1). Both of these pests are migratory, making it difficult to predict where populations will establish year to year.

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

We ask for volunteers around the state to set up traps (Figure 2) to monitor BCW and TAW flights in Iowa. This year, 36 volunteers established 39 traps of each species (78 total traps!) in 34 counties in Iowa.

armyworm moths in sticky wing trap
Figure 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. An intensive 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.

No significant flights of BCW occurred during the first two weeks of moth trapping.

Week 1:

No moths were reported in March, but reports quickly spiked the first week of April. The first TAW flights occurred April 1, and the first BCW flights occurred April 2. Counties with reports are shown in Figures 3 and 4.

TAW Reports March to April 4 2020
Figure 3. True armyworm moth captures from March 22 to April 4. The total moth count for the time period is noted on the map; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 22, 2020.

BCW Reports March to April 4 2020
Figure 4. Black cutworm moth captures from March 22 to April 4. The total moth count for the time period is noted on the map; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 22, 2020.

Week 2:

April 6 and April 8 had the highest reports to date. On April 6, 23 TAW and 8 BCW moths were caught across the state. On April 8, 23 TAW and 6 BCW were caught across the state. Counties with reports are shown in Figures 5 and 6.

TAW Reports April 5 to 11 2020
Figure 5. True armyworm moth captures from April 5 to April 11. The total moth count for the time period is noted on the map; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 22, 2020.

BCW Reports April 5 to 11 2020
Figure 6. Black cutworm moth captures from April 5 to April 11. The total moth count for the time period is noted on the map; highlighted counties without numbers indicate that traps are placed but no reports have been received. Data is current as of April 22, 2020.

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 Extension Program Specialist III

Ashley is an extension program 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