The European Corn Borer in Hops and Hemp

As the production of hemp and hops grows in the northeast, pests such as the European corn borer (ECB), Ostrinia nubilalis, are increasingly problematic for these crops. As the name suggests, ECB are a major pest of corn, though they can be damaging to hundreds of plants. The ECB caterpillars feed on and weaken plant stems, which can cause them to break, ultimately reducing quality and yields. If corn planting is delayed, ECB may shift to alternate hosts. Depending on the year, farmers have reported varying degrees of damage. Crops located near corn fields can be at higher risk. It is important to understand the lifecycle of the ECB, so proper monitoring and control measures can be put into place to minimize crop damage.

Scouting – Growers should monitor their crops for corn borers eggs beginning in early spring. Regularly scouting your crop is a cheap and easy way to monitor pest populations and potential problems that may arise. The ECB can easily be managed in their egg and larval stages, but once the caterpillars enter the stem or bine, they are more difficult to deal with. To scout your hemp and hop plants, examine the top and bottom of the leaves, on low and high portions of the plant stems. Choose random plants throughout your fields and hop yards to gain a representative view of the entire planting.

The ECB moth flights in June and August can also be monitored using pheromone-baited Scentry Heliothis net traps. Place two traps at least 50 feet apart along the edge of your field or hop yard, with the bottom of the trap above the top of grassy weeds, no higher than 4 inches above the vegetation. Avoid placing them over bare ground. Because there are two strains of ECB found in New England (New York strain and Iowa strain), bait one trap with a lure for each. Be sure to check the traps once or twice per week, and replace lures every other week. Several states in the Northeast maintain ECB monitoring networks geared towards sweet corn production (for example NY:, PA:, so you can get a general idea of when the ECB flights are occurring in our surrounding region. However, ECB distributions are notoriously patchy, so it is important not to become over reliant on data from other states, or even regions within states.

For more information on the Life Cycle and Management of corn borers, please read the European Corn Borer fact sheet found on our web site –

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