Insects & Worms in Sunflower Seeds

Sunflower seeds are used for a variety of purposes, including as a snack, bird feed and oil that can be used for cooking and in salad dressings. There are several types of insects and larvae that feed on sunflower seeds, which can lead to scarring on the plants. If these insects and their larvae are still present when the sunflower seeds are harvested, they can become mixed into the sunflower seeds that are produced.

The red sunflower seed weevil is one of two types of weevil that attack sunflower plant seeds. The larvae of these weevils have the appearance of worms and may be mistaken for worms. Red sunflower seed weevils are a problem in the northern United States and is especially prevalent in Minnesota, North Dakota and South Dakota. As an adult, the red sunflower seed weevil measures between 2.5 and 3 mm in length and is reddish-orange in color. The red sunflower seed weevil lays its larvae inside developing sunflower seeds. The larvae affect the amount of oil the seeds produce and the weight of the seeds when they are harvested. On occasion, larvae are still inside the seeds when they are harvested and this can lead to holes in the sunflower seeds -- you might even eat a seed and discover it has a bitter taste, which is caused by the weevil larvae.

The gray sunflower seed weevil is more common in the southern area of the U.S. than the red sunflower seed weevil. The gray sunflower seed weevil produce slightly larger larvae and when they are implanted into developing sunflower seeds, they cause the seeds to become significantly larger than non-infested seeds. The gray sunflower seed weevil causes more damage to sunflower seeds than the red sunflower seed weevil because it consumes the entire kernel.

The sunflower seed maggot is one of three types of maggots that affect sunflowers. The sunflower seed maggot larvae feed on young and old sunflower plant heads and can cause sunflower seeds to become sterile due to the larvae tunneling through the head. These maggots are less destructive than the weevils are to the sunflower plants. As adults, sunflower seed maggots are yellow-brown in color and have wings.

Sunflower moths cause the most damage to sunflower plants in the U.S. The sunflower moth is shiny and gray in appearance, it deposits its eggs on the heads of sunflowers and the larvae feed on the pollen and ultimately leads to empty seeds being produced by the plant. Sunflower moth infestations can be very severe and lead to significant losses in terms of seed production and quality.