ECB and CEW moth catch thresholds for processing snap beans

(bud stage – harvest)

European corn borer (ECB)

Sampling: Sampling is based on monitoring moth catches in local blacklight traps. For the most precise decisions, traps should be placed within one mile of each field. Traps should be serviced 3 times per week, preferably daily when moth activity increases.

The most critical time for corn borer treatment occurs at the bud-early bloom and pin stages. As a general guideline, treatment should begin when trap catches average 5 ECB moths per night. However, if moths can be observed readily in a field and trap catches have not reached 5 per night, sprays should still be applied at the bud-early bloom and pin stages. After the pin spray, the following thresholds and spray intervals should be used:


Number ECB Moths per 5 Days
Spray Interval
Less than 10
No Spray
11 – 25
7 Day
25 – 50
6 Day
51 – 75
5 Day
76 – 250
4 Day
250 +
3 Day

Corn earworm (CEW)

Sampling: Blacklight traps, pheromone traps, and direct observation of moths in fields should be used to monitor moth activity. A standard drop cloth can be used to detect small larvae.

Thresholds: As a general guideline, sprays should be applied on a 3-7 day schedule when blacklight trap catches exceed 20 per night. The spray interval will vary depending on corn borer moth activity and temperature.