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Lep Monitoring Network – Corn Earworm Update # 11

western bean cutworm pheremone trap at edge of corn field

Here at the Lep Network, we have concluded our eleventh week of monitoring for Ohio pests and are on our second week of western bean cutworm moth reports and our fourth week of corn earworm! This past week, Wood County saw the highest average of WBC moths with a whopping 17 in Figure 1. Yellow striped armyworm moth. Photo credit: Rebekah D. Wallace, University of Georgia, Bugwood.orgone trap, and Clinton County saw the highest for CEW. Similar to last week’s report, Van Wert County once again saw an influx of yellow striped armyworms (Figure 1) in their WBC traps – the county has 10 running traps and recorded an average of 6.0 YSA moths per trap this past week, an average of 3.9 more than last week.

Western Bean Cutworm
This past week was our second week monitoring for WBC in Ohio. The statewide average for WBC decreased from 1.8 during the week ending on June 23rd to 0.7 for the week ending June 30th. Counties with the highest averages included Wood (17.0), Defiance (5.3) and Van Wert/Hancock (3.0) (Figure 2). As mentioned in previous newsletters, WBC is a common pest of dry beans and a sporadic pest of corn in Ohio. Adults are primarily dark brown and black and can be identified by a distinct comma or crescent-shaped mark in the middle of each wing that is seated behind a light brown to tan colored dot. A white stripe can also be seen along the top edge of the forewing (Figure 3). WBC adult emergence typically takes place from late June to early July, so be sure to keep a look out for this pest.

When monitoring for WBC, it is important to be aware of imposters that may find their way into WBC traps and are easily confused with true WBC moths. The imposter WBC’s look practically identical to their harmful counterparts and the primary distinguishing feature between the two is size. Imposters tend to be significantly shorter in length when compared to true WBC’s (Figure 4). To continue the conversation and learn more about the western bean cutworm, please visit: https://ohioline.osu.edu/factsheet/ENT-40

Western bean cutworm moth map
Week 2
June 24th to June 30th, 2024

Figure 2. Average western bean cutworm (WBC) moths captured from June 24th to June 30th. 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 number of active traps set up in that county.

 

 

Figure 3. Western bean cutworm on an ear of corn. Photo credit: Adam Sisson, Iowa State University, Bugwood.org

Figure 4. Imposter WBC (left) next to true western bean cutworm (right). Photo credit: Stephanie Pflaum, The Ohio State University OARDC.

Corn Earworm
This is our fourth week monitoring for CEW pests in Ohio. The statewide average for CEW decreased from 1.6 during the week ending on June 23rd to 0.4 for the week ending June 30th. Counties with the highest averages included Clinton (3.0), Trumbull (3.0) and Morgan (3.0) (Figure 5). Corn earworm moths tend to be attracted to fields that are in the early green silk stage of development; this is when fields will be most susceptible to damage. CEW caterpillars vary in color from light to dark but will always have the same characteristic markings. Scouting for the larval stage of these pests is practically impossibly, but adult (Figure 6) scouting is important to predict larval damage in a field. To learn more about the corn earworm, check out one of our previous newsletters: https://agcrops.osu.edu/newsletter/corn-newsletter/2019-27/corn-earworm-field-corn-watch-molds

Corn earworm moth map
Week 4
June 24th to June 30th, 2024
Figure 5. Average corn earworm (CEW) moths captured from June 24th to June 30th. 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 number of active traps set up in that county.

 

 

Figure 6. Corn earworm moth. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org

 

 

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.