Caterpillars are Eating My Sunflower Plants

Types

• The larvae of the sunflower moth (Homoeosoma electellum), banded sunflower moth (Cochylis hospes) and sunflower bud moth (Suleima helianthana) are the three most commonly found caterpillars on sunflowers. It's the first, the sunflower moth, that usually does the most damage, according to the University of Missouri. Other caterpillars found on sunflowers include the striking "painted lady" caterpillar and the larvae of the sunflower midge and sunflower beetle.

Damage

• The sunflower, banded sunflower and bud moths all focus on different areas of a sunflower. Sunflower moth larvae primarily feed on parts of the flower, but they also tunnel into the seeds. Banded sunflower moth larvae also tunnel into the seeds and eat the meat. Bud moth larvae feed on the stem and flower head. Holes in the stem near the leaves and damage flower heads are common symptoms of the bud moth, according to Purdue University. Less common caterpillars usually feed on the foliage, causing the edges of the leaves to become ragged or holes to appear in the middle of the leaves.

Control

• If you only see a few caterpillars on your sunflowers, the easiest way to get rid of them is to slip on some gardening gloves and pluck them off by hand. Drop the caterpillars in a bucket of soapy water to drown them. Otherwise, serious infestations can be controlled with an application of insecticidal spray or oil. Insecticides should only be used when severe damage from caterpillars is apparent, as they can also kill beneficial insects such as ladybugs. Use an insecticide approved for sunflowers, and follow the directions on the package as per the size of your sunflower plot. If you do use an insecticide on your sunflowers, be sure to thoroughly wash the seeds after you harvest them.

Considerations

• Caterpillars may not be the only thing eating your sunflower plants. Beetles are also common insect pests, but the major pest of sunflowers are birds, who love the tasty seeds. Protect your sunflowers from birds by slipping a paper or plastic bag over the sunflower head when it is ripe and the seeds are drying. You'll know the head is ripe when the back of the sunflower head turns brown. Or, cut the flower heads off as soon as the back of the head turns brown and spread them out to dry in a protect location.