How to Manage Pests

UC Pest Management Guidelines


Seedcorn Maggot

Scientific name: Delia platura

(Reviewed 11/05, updated 1/10, pesticides updated 9/16)

In this Guideline:


Larvae of the seedcorn maggot are small, pale or dirty-colored, yellowish white, legless maggots with tough skin. Adults are grayish brown flies and about 0.20 inch long.


Seedcorn maggots feed on the seed and may destroy it. Injury is most severe during wet, cold periods.


In California, seedcorn maggots are only occasional pests. They are usually associated with high levels of organic matter in fields that have recently had a cover crop disked in.

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
  (Thimet 20G) –at planting 3.4–4.5 oz/1000 row ft 72 30
  (Thimet 20G) – postemergence 4.9–7.5 lb   30
  COMMENTS: Apply at planting; do not place granules in direct contact with seed. Do not feed tops to livestock.
  (Lorsban 15G) 4.5–9 oz/1000 row ft 24 30
  COMMENTS: In-furrow at planting time. T-band or band at planting or postemergence. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.

Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
1 Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Sugarbeet
UC ANR Publication 3469

Insects and Mites

E.T. Natwick, UC Cooperative Extension Imperial County

Acknowledgement for contributions to Insects and Mites:
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, Kern County
L. D. Godfrey, Entomology, UC Davis

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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