2021 Iowa Moth Trapping Network Update: Week 8

May 26, 2021 12:17 PM
Blog Post

For the first time during the 2021 moth trapping season, more total true armyworm moths were reported than black cutworm moths. During Week 8 of the Iowa Moth Trapping Network, our cooperators reported 109 total black cutworm (BCW) and 128 true armyworm (TAW) moths.

Week 8 report:

The TAW moths reported during Week 8 were captured statewide and throughout the entire week, but most TAW moths were reported on May 17 (Figure 1). Reports of BCW were also statewide but sporadic throughout the week (Figure 2). New significant flights of BCW were reported in the following counties:

  • Taylor County (SW) – May 17; projected cutting date: June 3
  • Benton County (EC) – May 19; projected cutting date: June 5
  • Washington County (SE) – May 19; projected cutting date: June 4

Reports that indicated a potentially significant flight took place include the following counties:

  • Plymouth county (NW) – May 19; projected cutting date: June 5
  • Floyd (NC) – May 20; projected cutting date: June 5
  • Tama (C) – May 20; projected cutting date: June 5

What does this mean? You may recall that we predicted cutting dates for black cutworm earlier this month. Those predictions were based on significant flights that occurred during April and are still relevant. Those dates represent a starting point for scouting corn for cutting and larvae. Moths continue to migrate into Iowa and lay eggs. The new significant flights and projected cutting dates may be used as a guideline for scouting. You can also see them on the 3rd map at https://corn.ipmpipe.org/insects/black-cutworm/.

Remember that scouting should confirm that plant damage has occurred, larvae are present in the field, and larvae are still actively cutting plants (< 1 ½ inch long) before a treatment decision is made. Corn is not considered susceptible to cutting once plants reach the V5 growth stage.

TAW reports May 16 to May 22 2021
Figure 1. True armyworm moth captures from May 16 to May 22. The bold number indicates the total moth count for the week, while the smaller number in parentheses is a running total of the moth count for the season; highlighted counties without bold numbers indicate that traps are placed but no reports have been received. Some counties have multiple sites; therefore, data is only reported for the site with the highest count during the week. Data is current as of May 26, 2021.

BCW reports May 16 to May 22 2021
Figure 2. Black cutworm moth captures from May 16 to May 22. The bold number indicates the total moth count for the week, while the smaller number in parentheses is a running total of the moth count for the season; highlighted counties without bold numbers indicate that traps are placed but no reports have been received. Some counties have multiple sites; therefore, data is only reported for the site with the highest count during the week. Data is current as of May 26, 2021.

These updates are typically a week behind. Stay up-to-date by visiting https://corn.ipmpipe.org/insects/ to see live mapping from Iowa, Wisconsin, and Illinois.

Follow these links to see the reports from Week 1, Week 2, Week 3, Week 4, Week 5, Week 6, and Week 7.

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:

Category: 
Crop Production
Insects and Mites
Tags: 
cutworm
armyworm
corn pests
insect trapping
Author: 

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 ...