Corn Earworm Flight Has Started- Scouting Tips

(Updated: July 21, 2023, 9:24 a.m.)

Corn earworm moth catches have been ticking up across the state this week, especially in southern counties of the state. Any soybeans that are blooming are highly attractive places for moths to lay eggs. Soybeans that have pods (R3+) are less attractive as locations for them to lay eggs.

Start scouting for corn earworm in soybeans at R3 (beginning pod). We have several resources on scouting. Scouting for Insects on the NCCE soybean portal has a section dedicated to corn earworm sampling. On this page, you can find a link to a

using a sweep net, drop cloth, and how to use the online threshold calculator for corn earworm. We also have the NC Soybean Scouting Guide, with tips for corn earworm scouting on page 82. Finally,

describes how to scout for mid-season soybean insect pests.

Keep in mind that we can tolerate very very high levels of corn earworm in blooming soybeans (R1 and R2). So it's not a good idea to tank mix insecticides with fungicides for a few corn earworms. Let biocontrol agents do their job! Also, be sure to scout for stink bugs- they are most damaging from R3 (beginning pod) to R5 (beginning seed). Stink bug thresholds are here.

Here are a few good-practice tips for scouting insect pests in soybean (modified from Jack Bacheler):
  1. Good scouting will pay for itself more if growers can
    1. Break up a farm into individual management zones. Think about things like planting date, maturity group, field size, historical pressure
    2. Hire a specialized professional
      1. Grower time is valuable and farms are becoming larger
      2. Insecticide choice is often nuanced, dependent on correct species identification, quantification, and expected future pest pressure
      3. Growers often won’t take random samples because they don’t want to miss any damage. They are emotionally invested!
      4. Check behind the professional for quality control
      5. Reliable scouting is hot and tedious work in July, August, and September

 
  1. Scouting equipment should include a sweep net for narrow rows, a drop cloth for wider rows (30” or more), a knife for splitting stems, a hand lens, and something to record data

 
  1. Do not scout field borders (unless you want to find edge associated species like stink bugs and kudzu bugs), under power lines or other obstructions, and vigorously growing areas since they tend to harbor more pests

 
  1. Scouts should record exactly what is found in a timely manner, without over or underestimation