Sunflower Seed Maggot: Appearance, Territory, Damage and Life Cycle

Latin Name: Neotephritis Finalis

Appearance: The mature sunflower seed maggot measures 0.25 inches in length. The wings are covered in a brown lacelike design. At adulthood, the larvae are 0.19 inch in length. The little brown pupa is located on the face of the sunflower bud, frequently surrounded by a few broken florets. This maggot has two generations in North Dakota and, most likely, Canada. Adults appear in North Dakota in early July, and eggs are placed on growing buds.

Hosts Plants: Sunflower seed maggot larvae eat on young and elderly sunflower plant heads, and their burrowing through the head can cause sunflower seeds to become infertile. These maggots are less damaging to sunflower plants than weevils are.

Territory: This maggot has two generations in North Dakota and, most likely, Canada. Adults appear in North Dakota in early July, and eggs are placed on growing buds.

Damage Insect Cause: Sunflower receptacle maggots and sunflower seed maggots have caused no damage. The extent of damage caused by sunflower seed maggot larvae to sunflower seeds is mostly determined on the stage of larval and seed development. When freshly born larvae burrow into the corolla of immature blossoms, they cause seed sterility. According to observations, a single larva feeding on immature flowers will burrow through 12 ovaries. Mature larvae that feed on older sunflower heads will only consume one to three seeds.

While sunflower maggot infestations have occasionally reached near 100%, damage from larval feeding is typically minor. A commercial sunflower crop adjacent to a grassed canal or other water source may support a higher-than-normal infestation. Under these conditions, large larval numbers of eight to ten per stalk are possible, and stalk breaking is possible. Stalk breakage has been seen in up to 30% of the plants.

Life History and Habits: Sunflower maggots reproduce once a year. This bug spends the winter as a larva on plant waste in the soil. Early June marks the end of pupation and adult emergence. Females deposit eggs in immature sunflower stem tissue, and larvae eat in the pith tissue for the majority of the growth season.