Bean seed fly

Delia platura

Introduction:

Delia platura, commonly known as the seedcorn maggot, is a small but significant agricultural pest belonging to the family Anthomyiidae. This insect poses a threat to a variety of crops, especially those with seeds or young plants, making it imperative for farmers and gardeners to be able to identify and manage this pest effectively.

Appearance:

The adult Delia platura is a fly with a length ranging from 4 to 6 mm. It typically has a grayish-brown coloration and displays distinctive black bristles on its thorax. The wings of the seedcorn maggot are transparent, and the abdomen may have a subtle metallic sheen. The larvae, or maggots, are legless and cylindrical, with a white or cream coloration.

Identification:

Identifying Delia platura involves examining both the adult and larval stages. Adult seedcorn maggots are typically observed in the vicinity of crops during the spring and early summer. Monitoring for adult flies and their distinctive bristle-covered thoraxes can aid in early detection.

The larvae, responsible for causing damage, are found in the soil around the seeds and seedlings. Seedcorn maggot larvae have a pointed head and a tapered rear, and their creamy-white coloration distinguishes them from other soil-dwelling pests. Seedlings attacked by Delia platura often exhibit wilting, yellowing, and stunted growth.

Life Cycle:

Understanding the life cycle of Delia platura is crucial for effective management. The adult flies lay their eggs in the soil, and upon hatching, the larvae feed on germinating seeds and young seedlings. The maggots then pupate in the soil before emerging as adult flies, completing the cycle.

Management Strategies:

  1. Crop Rotation: Implementing a crop rotation strategy can disrupt the life cycle of Delia platura, as the larvae depend on specific host plants. Rotating to non-susceptible crops can help reduce infestations.

  2. Early Planting: Planting crops early in the season can allow them to mature before the peak activity of seedcorn maggot larvae, reducing the risk of damage.

  3. Seed Treatment: Treating seeds with insecticides before planting is an effective preventive measure. This protects the seeds and emerging seedlings from maggot infestation.

  4. Biological Controls: Beneficial organisms such as predatory beetles, parasitic wasps, and nematodes can be employed as natural enemies to control Delia platura populations.

  5. Sanitation: Removing crop debris and weeds from the field can eliminate potential breeding sites for Delia platura, reducing the risk of infestation in subsequent plantings.