It is week 2 of monitoring Lepidopteran pests in ag crops across Ohio, and despite all of the rain over the past week the temperatures continue to increase and we are continues to see counties with high numbers of black cutworm (BCW) and true armyworm (AMW) moths. Read below for more information.
Black cutworm
Over the past week BCW moth trap numbers remained high across Ohio with many monitoring counties reporting moths in their traps. Overall, we monitored a total of 49 traps in 17 counties. Our statewide average was lower (9.3) compared to last week’s average of 20.1 moths. We recommend keeping a close eye on fields in counties with averages of 7 moths or more per week. This week those counties include Auglaize, Defiance, Hardin, Henry, Huron, Lorain, Lucas, Van Wert and Wood (Figure 1).
A reminder from last week: Black cutworm moths are specifically attracted to fields with broadleaf weeds, such as chickweed (Figure 2) and purple dead nettle (Figure 3). The moths fly into these area and lay eggs, which then hatch in 5 – 10 days, and larvae go through 6 instar stages over the next 28 – 35 days. Counties with high trap numbers should plan to scout for BCW larvae after corn is planted until V6 stage, especially in fields with a lot of broadleaf weeds (such as chickweed and purple dead nettle). For more information on how to scout BCW please visit: https://aginsects.osu.edu/sites/aginsects/files/imce/ENT_35_14 BCW.pdf
Black cutworm moth map
Week 2
April 28th to May 4th, 2025
Figure 1. Average black cutworm (BCW) moths captured from April 28th to May 4th. The bold number on the left indicates the average moth count for the week, followed by the standard number on the right which indicates the total traps set up in that county.
Figure 2. Common chickweed. Photo credit: Curtis Young.
Figure 3. Purple dead nettle. Photo credit: Amy Raudenbush.
True Armyworm
Over the past week the Lep Network also monitored 47 traps in 17 counties for true armyworm (Figure 4). Our statewide average from last week was also lower for AMW (4.7) compared to the previous week with 15.3 moths. Counties with a weekly average of 7 moths or more included: Auglaize, Henry, Van Wert and Wood.
A reminder from last week about AMW: Adults lay eggs in grasses and rye cover crops. The eggs hatch and feed on young corn plants. Counties with high trap numbers should monitor for AMW larvae after corn is planted, especially in areas of grassy no-till fields or fields that had rye cover crop.
True Armyworm moth map
Week 2
April 28th to May 4th, 2025
Figure 4. Average true armyworm (AMW) moths captured from April 28th to May 4th. The bold number indicates the average moth count for the week, and the standard number in parentheses is the total number of traps set in that county.
Lastly, an update from Curtis Young (Van Wert County) who has been monitoring variegated cutworm activity beside a clover cover crop field. The egg masses he noticed last week have successfully hatched into first instars as of this week (Figure 5). The damage young larvae cause is usually not noticeable – but as the larvae grow, they eat more and feeding becomes more apparent. That is why it’s important to continue to scout your field corn until V6.
Figure 5. Variegated cutworm first instars hatching from eggs, early May 2025. Photograph taken by Curtis Young.