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Ohio State University Extension

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Lep Monitoring Network – Western Bean Cutworm numbers are on the rise #12

This is our 12th week of monitoring moth pests in Ohio. Between July 7th and July 13th, we continued to monitor Corn Earworm (CEW) and Western Bean Cutworm (WBC). Over the past week, the state of Ohio experienced mild rainfall and average temperatures (75.9 °F), which may have led to an increase in WBC activity. The statewide averages for CEW remained low. Please read below for more details.

Western Bean Cutworm

This week 21 counties monitored WBC (Figure 2) with a total of 56 traps. Nineteen counties trapped WBC this week, which is an increase from the previous week. Moth counts were greater than what we have seen so far this season, and the average moths per county was 5.40. Counties with the highest averages included Sandusky (25.0), Lucas (16.0), Defiance (13.8), Fulton (13.7), Henry (10.3), and Wayne (7.5) (Figure 2). The numbers for WBC are expected to remain high, so counties with an average greater than 7.0 moths should consider inspecting their fields.

How to scout for WBC egg masses

Figure 1. Western Bean Cutworm. Photo credit: Amy RaudenbushA field of corn that is in the process of forming tassels is an ideal place to start looking for WBC eggs. Examine 20 plants in 5 different locations (100 plants total). Typically, eggs can be found on the underside of upright leaves near the tassel or on the upper side of leaves near the leaf collar. Newly laid eggs are usually a whitish color, and the older eggs can be dark purple (Figure 1). Treatment options should be considered if 5% of plants have egg masses. For optimal results, treatment should be applied when the majority of the eggs found are purple.

To view a more detailed video on scouting – click here: https://youtu.be/qGjpwtfkObM?si=CFPzX1rlqt6jzyJw

For more information on how to scout WBC please visit: Western Bean Cutworm | Ohioline

Western Bean Cutworm Moth Map
Week #6
July 7th to July 13th, 2025

Figure 2. Average Western Bean Cutworm (WBC) moths captured from July 7th to July 13th. The bold number indicates the average moth count for the week. The standard number indicates the total number of traps in that county.

Corn Earworm

Figure 3. Corn earworm moth. Photo credit: Curtis Young, OSU

This week we monitored 35 traps in 16 counties across Ohio. Similar to last week, there were low numbers of CEW (Figure 4) across the state with an average of 0.44 moths per county (Figure 4). Morgan County had the highest moth average, which was 2. Overall, the statewide averages of CEW have remained low since the beginning of June.

More information on CEW can be found here: Corn Earworm in Field Corn; Watch for Molds | Agronomic Crops Network
 

Corn Earworm Moth Map
Week #6 
July 7th to July 13th, 2025
Figure 4. Average corn earworm (CEW) moths captured from July 7th to July 13th. The bold number indicates the average moth count for the week. The standard number indicates the total number of traps in that county.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.