Hop vine borer

The hop vine borer (Hydraecia immanis) is a moth species belonging to the Noctuidae family within the order Lepidoptera. While primarily recognized for its damage to hops, it has emerged as a notable economic pest for corn crops, particularly in regions where corn is planted near fields with long-standing infestations or grassy areas.

The life cycle of Hydraecia immanis is univoltine, meaning there is only one generation per year. Eggs are laid in the late summer or autumn and overwinter in the soil or on plant debris. Larvae emerge in the spring, and it is this larval stage that is responsible for all the economic damage to cultivated crops.

The primary damage is caused by the larvae boring into the base of the plant stem. In young corn, this causes the characteristic "dead heart" symptom, where the central whorl leaves wilt and die while the outer leaves remain temporarily green. As the larvae grow, they may move from plant to plant, increasing the total area of crop loss significantly.

Weed management plays a critical role in controlling this pest. Adult moths are attracted to grassy weeds, such as quackgrass (Elymus repens), for oviposition. If a field has a heavy infestation of such weeds prior to planting, the risk of larval transfer to the emerging crop is extremely high, leading to stand reduction.

• Practice clean cultivation to eliminate host weeds like quackgrass.
• Implement crop rotation to disrupt the life cycle of the moth.
• Utilize pheromone monitoring to predict adult flight and peak egg-laying times.
• Apply soil insecticides or foliar sprays based on scouting thresholds during early plant development.