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Seedcorn Maggot

Seed Corn Maggot Infesting Corn Seed
Seedcorn maggot infesting a corn seed.

Delia platura

Also known as: bean seed fly
Impacts: Corn, soybeans, dry beans, large-seeded crops
Time for concern: Spring

NYSIPM Researching Alternative Controls for Seedcorn Maggot (SCM)

The New York State Integrated Pest Management (NYSIPM) Program and NYS Agriculture and Markets are evaluating alternative seed treatments for seedcorn maggot. 

Fields with manure applied or cover crops that have been terminated and tilled under are more attractive to seedcorn maggot. Because these are common practices, NYSIPM is evaluating diamide and spinosad seed treatments as potential alternatives to neonic insecticides at locations across New York State.

Studies in Progress

  • Risk Assessment Model—develop a multi-factorial (weather, climate, local management, and land use surrounding a farm) model to anticipate the occurrence and abundance of SCM and the need for intervention.
  • Cover Crop—determine the effect of using red clover as a cover crop on SCM damage to corn in a subsequent rotation.
  • Lures—find the most effective lure for monitoring SCM and determine if deploying them as traps can decrease pest pressure.
  • Jasmonate—evaluate an organically derived seed treatment with the potential to deter SCM damage.
  • Spinosad—evaluate an alternative seed coating insecticide to decrease SCM damage

Seedcorn Maggot Damage

Seedcorn maggot (Delia platura) is an early-season pest of large-seeded crops such as field corn and soybeans. The adult flies lay eggs in field soil early in the spring. When maggots hatch looking for food, they find large, germinating seeds, burrow into them, and feed. This kills the seed or greatly reduces the health of the emerging plant. Damage is more severe in cool, wet spring weather, as it delays seedling emergence. In some cases, the economic impact of seedcorn maggot can be so great that fields may need to be replanted. 

Adults

Seedcorn maggot adults resemble the common housefly. Females lay eggs in moist soil cracks, high organic matter, decomposing plant material, and germinating seeds.

Maggots

Maggots are pale, yellowish-white, tapered, legless, appear to be headless, and reach a length of about one-quarter inch. They burrow into germinating seeds to feed.