How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Seedcorn maggot larvae are legless, white maggots that cannot be distinguished from cabbage maggots without microscopic examination by a trained taxonomist. However, unlike cabbage maggots, they do not attack plants after seedling stages, so are rarely found tunneling in larger roots. The life cycle is similar to cabbage maggot with adult flies laying eggs singly or in clusters in the soil near plant stems. Larvae feed for 1 to 3 weeks on seeds and germinating seedlings and burrow into the soil to pupate. Numerous generations may occur, although maggots are most prevalent under cool spring conditions, especially after wet winters, and populations may decline in summer. This insect is attracted to soils that have a high organic matter content.

DAMAGE

Seedcorn maggots kill germinating seed and very small seedlings. Once the stand is established and seedlings have developed a few leaves, they are unlikely to cause economic damage.

MANAGEMENT

Prevention is the best management strategy. Seedcorn maggots prefer to lay their eggs in moist, organically rich soil. If you are using manure, let it age and incorporate it well before planting. Disk under cover crops at least 2 weeks before planting. Attach drag chains behind the planter during seeding to reduce egglaying in the seed row. Cool, wet spring weather is favorable to the development of seedcorn maggot populations.

Monitoring and Treatment Decisions
Treatment for seedcorn maggots is not generally necessary, especially in coastal areas. However, in the Central Valley, spring-planted fields with high organic matter may require treatment if not rotated to grains or other nonhosts. Preventive treatments applied for cabbage maggot prevent seedcorn maggot problems.

PUBLICATION

UC IPM Pest Management Guidelines: Cole Crops
UC ANR Publication 3442
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgments for contributions to Insects and Mites:
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
W. E. Chaney, UC Cooperative Extension, Monterey County
N. C. Toscano, Entomology, UC Riverside

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