Bean, lima-Seedcorn maggot

Delia platura

Pest description, crop damage and life history


Pest monitoring Slow emergence and poor stand establishment are signs of seedcorn maggot activity. Where slow, spotty emergence is observed, dig up seed and inspect it for maggot feeding. Cool soil temperature and periods of excessive moisture favoring slow seed germination and seedling emergence resulting in increased susceptibility to seedcorn maggot infestation. To assess potential infestation levels prior to planting, place a cut potato or other vegetable or fruit in the field and apply baker's yeast with some water to the cut surface. Leave the bait for several hours and return to look for the presence of adult seedcorn maggot flies as they are attracted to carbon dioxide.

Management-cultural control

To reduce attractiveness of the field to egg-laying adults, disc or plow early in the year, incorporating residues from a previous crop and destroying weed growth. Plant under ideal soil and weather conditions to assure rapid seed germination and minimize the seedcorn maggot problem.

One of the most reliable control methods now in general use is to plant seeds that have been treated with an appropriate insecticide in the seed box at planting. Practically all commercially available seed corn is treated with an insecticide to protect the seed from insect pests during storage. However, this treatment is not sufficient to provide field protection against seedcorn maggots. A planter box seed treatment insecticide at planting is recommended.

Management-chemical control: HOME USE

  • bifenthrin (may be combined with zeta-cypermethrin)
  • pyrethrins (often combined with other ingredients)-Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin

Management-chemical control: COMMERCIAL USE

  • chlorpyrifos (Lorsban Advanced)-As a broadcast or T-band treatment prior to planting. Consult label for rates. Do not exceed 0.94 lb ai/a per year.
  • phorate (Thimet 20-G)-Do not exceed 1.5 lb ai/a. PHI 60 days. REI 48 hr, or 72 hr if annual rainfall is less than 25 inches. Apply at planting. Do not graze or feed to livestock. Toxic to fish and wildlife.