Figure 1. Banded sunflower moth adult. Courtesy: Janet Knodel, NDSU
Banded Sunflower Moths
It is getting close to that time of year again when sunflower growers should be scouting sunflowers for insect pests that directly affect the head and developing seeds. One of the more important pests to scout for is the banded sunflower moth due to its potential to reduce yields. Banded sunflower moths cause injury to the plant when the caterpillars begin feeding on the developing florets and tunnel into the seeds. This activity can inhibit pollination and decrease the number of viable seeds per head.
Description & Behavior
Banded sunflower moths are approximately ¼ of an inch long, and have a wingspan that is approximately half of an inch. The moths are a white to cream color and have a distinct dark brown band that runs across their wings (Figure 1). Banded sunflower moth caterpillars can vary in color, depending on their development stage. Young caterpillars will be white or cream colored. During the later stages of their development, the caterpillars will be pink or red in color. At the final stages, the caterpillars are green and approximately 7/16 of an inch long (Figure 2). Banded sunflower moth eggs are very small and white in color (Figure 3).
Banded sunflower moths overwinter in South Dakota and emerge as adult moths from late June through July. Soon after emergence, the moths begin laying eggs on the bracts of the sunflower heads. Egg laying typically peaks during late bud stages. The caterpillars hatch about a week after the eggs are laid and start feeding on the sunflower heads. The caterpillars may be found on sunflowers from July through September. Once the caterpillars have matured, they drop to the ground and pupate in the soil where they overwinter.
Fig. 2. Banded sunflower moth caterpillars. Courtesy: J. Knodel
Fig. 3. Banded sunflower moth eggs. Courtesy: J. Knodel
Scouting for banded sunflower moths should begin when the majority of the sunflowers in the field have midsized buds (R3 growth stage). Moths can be scouted for by either examining plants for egg masses or by looking for the adult moths.
For egg scouting, examine the outer six bracts of five sunflower plants located approximately 21 feet in from the field edge. This scouting method should be done on each side of the field for a total of four sampling sites. For each sunflower plant, count the number of eggs that are present on the outer layer of six floral bracts. Using a hand lens or magnifying visor may be helpful as the eggs are very small in size. As mentioned, scouting for eggs should begin when the majority of the field has reached the R3 growth stage. Eggs may be found in singles or as clusters.
Economic Injury Level
An economic injury level (EIL) calculator has been developed by researchers at NDSU.
In addition to the economic injury level, this tool also calculates the economic distance (ED) of the banded sunflower moth.
This distance (in feet) estimates how far into the field from the edge an economic population exists. A benefit of using eggs for scouting is an increased amount of time to make a management decision.
Banded sunflower moths can also be scouted by checking for adult moths on plants that are in the R3 growth stage. To scout for moths, select five sites that are 75 to 100 feet in from the field edge. These sites should be in a random pattern, and can be selected by walking in an “X”, “W”, or “Z” pattern. At each sampling site, examine 20 plants on the upper and lower sides of the leaves for a total of 100 plants. The economic injury level for this method of scouting is typically between 1 and 2 banded sunflower moth adults per 100 plants.
For management of the banded sunflower moth please refer to the current version of the South Dakota Pest Management Guide: Alfalfa and Oilseeds.