The Seedcorn Maggot is a pest of corn, usually seen early in the growing season. The maggots feed on seeds, so infected corn stalks never emerge from the soil.

Seedcorn Maggot Life Cycle Stages

Seedcorn Maggots overwinter as pupae in the soil, and adults emerge in late spring or early summer. Adults mate and lay eggs on organic matter, or decayed plant material. Seedcorn maggots emerge from eggs and burrow into the soil, where they feed on seeds.

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

Calculating Growing Degree Day Units

The Seedcorn Maggot Emergence Growing Degree Day model uses a lower threshold of 39Fand an upper threshold of 84.2F. 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 342 GDD. This can be used an approximate target for beginning to field scout for adult flies.

Source:

Funderburk, J. E., L. G. Higley and L. P. Pedigo. 1984. Seedcorn maggot (Diptera: Anthomyiidae) phenology in central Iowa and examination of a thermal-unit system to predict development under field conditions. Environ. Entomol. 13: 105-109.