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Agronomic Crops Network

Ohio State University Extension


Lep Monitoring Network Update #11 – Time to Scout for WBC!

The Ohio Lep Network is continuing to monitor moth pests across Ohio. As we enter our eleventh week of reporting, we continue population reports on Western bean cutworm (WBC), corn earworm (CEW), and both variations of European corn borer (ECB - IA & NY).

While monitoring for black cutworm (BCW) and true armyworm (AMW) have both ended for this season, it should be noted that Van Wert County, which had been seeing an increase of both pest species for the past couple of weeks, is finally beginning to see a decrease in these numbers. This week Van Wert County reported an average of 7.2 BCW (a steep decrease from the 19.5 average last week), and an average of 6.6 AMW compared to the 9.6 average of last week.

For more information on these pests and many more, check out our website:

Watching the Western Bean Cutworm
This is our fourth week reporting on adult Western bean cutworm (WBC) populations across Ohio. Overall, 22 counties have been monitoring for WBC, using 74 traps. The county reporting the highest average number of moths is Lucas County, with an average of 17 moths. Defiance and Henry counties also reported high averages of moths for the week (Figure 1).

Western Bean Cutworm Moth Map
July 11th – 17th, 2023

Figure 1. Average western bean cutworm moths (WBCW) captured from 11th – July 17th. The bold number on the left indicates the average number of moths captured. The second number on the right indicates the number of traps monitored in each county.

Counties with an average of 7 or more WBC should consider scouting for Western bean cutworm (WBC) egg masses. Numerous counties across Ohio have been seeing an increase of adult moths in traps over this past week. This uptick in numbers indicates that we are possibly nearing the peak week for WBC, and scouting for the egg masses will prove to be important for weeks to come.

Details on how to scout for WBC egg masses are described below or can be viewed here:

To scout for WBC eggs and larvae, choose at least 20 consecutive plants in 5 random locations within your corn field. In these locations inspect the uppermost 3-4 leaves for the eggs, as well as the silks of corn in case larvae have emerged. Eggs are laid in clusters and can be a range of colors – as the colors change as they develop, starting as an opaque white color, to a tan/orange color with a possible red ring, and then a final dark royal purple when they are near hatching (Figure 2). Larvae begin as small tannish caterpillars with dark heads when they first emerge from hatching. As they mature, they develop into an orangish-brown color but will have two distinct dark lines running down their body. When scouting be sure to inspect different areas of the field that may be in differing growth stages. Treatment is recommended for field corn, if 8% or more of the plants inspected have eggs or larvae, or for sweet corn if the percentage is 4% or more. WBC can do significant damage to corn in its larval stages, so scouting and monitoring population sizes is an important task, particularly for counties with higher risk. For more information regarding the Western bean cutworm, visit our website:

Figure 2. Various stages of WBC eggs. Eggs are laid in the uppermost 3-4 leaves of corn plants, and change color as they develop, starting with an opaque white coloration (upper left), turning tan/darker (upper right) and ending with a dark, almost royal purple (bottom left). Photo Credit: and M. Rice (bottom left). Also, newly hatched WBC larvae (bottom right). Photo Credit:

Chasing the Corn Earworm
This is our sixth week monitoring the corn earworm (CEW) pest. Overall, 12 counties have been monitoring 21 wing traps. The county with the highest reported average was Brown County, with an average of 25 moths (Figure 3).

Corn Earworm Moth Map
July 11th – 17th, 2023

Figure 3. Average corn earworm moths (CEW) captured from 11th – July 17th. The bold number on the left indicates the average number of moths captured. The second number on the right indicates the number of traps monitored in each county.

Corn earworm (CEW) is a common pest that we may see in Ohio corn, tomato, and legume fields. CEW is a more common pest for corn fields, specifically sweet corn fields. CEW moths lay their eggs on corn in the early green silk stage. Once the eggs hatch, the larvae cause feeding damage, attract birds, and invite the possibility of mold. CEW damage is seen near the tip of the corn, where most of the damage is reported. Identifying CEW larvae can be difficult, due to their variety of color variations. CEW larvae can range from various shades of brown to tan, green, and some even feature a pinkish hue. Adult moths are light brown and feature dark spots, as well as a large bold spot halfway between their body and wing. For more information on CEW and the threats they pose, check out our previous newsletter:

Exploring the European Corn Borer
This is our ninth week monitoring for the European corn borer across the state of Ohio. We have had 41 traps in 12 counties (Figure 4). We so far have only seen ECB IA, so only this variety is indicated on the map. This week no European corn borer adults were trapped throughout Ohio.

For more detailed information about the European Corn Borer visit our previous article at:

European Corn Borer Moth Map
July 11th – 17th, 2023

Figure 4. Average European corn borer moths (ECB) captured from July 11th – July 17th. The bold number on the left indicates the average number of moths captured. The second number on the right indicates the number of traps monitored in each county. Both variants had a total of 0 moths across all our counties in Ohio.

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.