Buttery Yellow Caterpillars on Sunflower Plants

Banded Sunflower Moth

• Sunflower farmers consider the banded sunflower moth (Cochylis hospes "Walsingham") to be a serious pest. The larvae are hairless, shiny, pale yellow caterpillars. The caterpillar feeds on the large flower heads, eating the flower and the seeds. The banded sunflower moth larvae can survive the cold winters of the northern Plains states by finding refuge in the dirt. The adult stage of the banded sunflower moth has champaign-and-white banded forewings and white, frilly back wings. Commercial sunflower growers are attempting to breed sunflowers that are resistant to the banded sunflower moth. Treatments include using pheromone traps, Bacillus thuringiensis applications. Experts don't recommend using broad range insecticides, which are harmful to beneficial insects.

Sunflower Bud Moth

• Sunflower bud moth (Suleima helianthana) is another shiny, pale yellow caterpillar that infests sunflowers. The sunflower bud moth normally eats mostly the stalk of the sunflower, but in some years, the larvae burrow into the unopened buds of the sunflower and reduce the seeds that the flowers normally produce. The moth has two life cycles during one summer, but only the first wave of larvae, in June, have real impact on the sunflower and its seeds. Since the caterpillar lives inside the sunflower, experts don't recommend treating the plant with insecticides because the spray won't reach the caterpillar.

Isophrictis

• Isophrictis similiella live in the stem and flower heads of sunflowers. These pale yellow caterpillars become small, beige moths with a fringed forewing tip and fringed hindwing. Bacillus thuringiensis is the recommended control method for these moths. Because the larvae live inside the plant, pesticides are not recommended. This species of moth seems able to live in small saplings as well as in sunflower stems.

Other Caterpillars

• Buttery yellow surface dwelling caterpillars that you may see on sunflowers include the fuzzy-banded Virginia tiger moth, or yellow woolly bear, (Spilosoma virginica), which becomes a white moth with a furry body. You might also see several members of the tussock moth family on sunflowers from time to time. These caterpillars are also yellow and furry, with a variety of spikes and dots on their backs, depending on the species. The fall webworm also can be pale yellow with long spikes of fur. The adult moth bears a luxuriously white fur coat and sports white wings with pale brown spots. These caterpillars do minimal leaf damage and can be eliminated by hand picking, spraying with BT or using a broad-spectrum insecticide.