How to Manage Pests
UC Pest Management Guidelines
Scientific name: Delia platura
(Reviewed 6/18, updated 6/18)
In this Guideline:
DESCRIPTION OF THE PEST
The seedcorn maggot adult is a slender, light-gray fly, about 0.2 inch (5 mm) long, resembling a small housefly. The whitish eggs are slightly curved and elongated, similar in shape to grains of rice. Slightly raised ridges run the length and width of the eggs forming tiny rectangles twice as long as wide. Larvae range from 0.2 to 0.25 inch (5–6 mm) in length. They are brownish white to whitish-yellow, cylindrical, and taper anteriorly. Pupae are small brown capsules. The seedcorn maggot is abundant during or following a wet cycle, which is primarily in spring (though this can also occur in fall on garbanzos). It is most common in fields containing high amounts of residue from previous crops or in fields where manure has been spread.
Seedcorn maggots burrow into bean seeds and prevent germination. Slow emergence and poor stand establishment are signs of seedcorn maggot activity. Where slow, spotty emergence is observed, seed should be dug up and inspected for maggot feeding. Cool soil temperatures and periods of excessive moisture delay seed germination and seedling emergence, which increase the susceptibility of bean seeds to seedcorn maggot infestation.
To prevent seedcorn maggot damage:
Organically Acceptable Methods
Use cultural controls for an organically certified crop.
Begin inspecting plants for seedcorn maggot damage when the crop emerges. If the stand is poor and emergence is sporadic, look for rotted seed in the soil. If any signs of infestation occur, use treated seed in the future.
UC IPM Pest Management Guidelines: Dry
Insects and Mites
R. F. Long, UC Cooperative Extension, Yolo County
Acknowledgment for contributions to Insects and Mites:L. D. Godfrey, Entomology, UC Davis