The Hop Vine Borer is a boring moth that is a major pest on corn. It is usally found in areas with grass, or grassy weeds, that early larvae can feed on. Larger larvae prefer to feed on corn or hops, and tunneling from larvae feeding can cause significant crop loss.

Hop Vine Borer Life Cycle Stages

Hop Vine Borers usually take one year to complete a generation. Hop Vine Borers overwinter as eggs on grasses, and resume feeding activities spring or late winter, growing before moving to corn or hops. These larvae then pupate and adults emerge in summer. Adults then feed and reproduce and females lay eggs on grasses.

The period of adult emergence is key for insect prevention, both for placing traps and for using insecticides, if necessary. Researchers have created the Hop Vine Borer Adult Emergence Growing Degree Day Model to better predict when the adults will emerge.

Calculating Growing Degree Day Units

The Hop Vine Borer Emergence Growing Degree Day model uses a lower threshold of 41.5F and an upper threshold of 75F. It can be calculated with daily high and low temperatures, using the sine model to estimate growing degree day units, or the Pest Prophet app can be used to calculate GDD accumulation from hourly temperature data for a specific field.

Using Jan. 1st as a default “biofix” date, or starting point for accumulation, the first adult emergence occurs at approximately 2385 GDD (F) and peak at approximately 3172 GDD (F). This can be used to guide pest management decisions and timing.

Source:

Levine, E. 1989. Forecasting Hydraecia immanis (Lepidoptera: Noctuidae) moth phenology based on light trap catches and degree-day accumulations. J. Econ. Entomol. 82: 433-438.