Sunflowers have a lot to offer a gardener, from colour in the landscape to striking cut flowers for bouquets to tasty seeds. They grow relatively easily in most areas but do occasionally suffer from pests that eat them.
Gardeners who see leaf or stalk damage on sunflower plants should inspect the plants for moth larvae, black weevils, winged yellowish, brownish or white maggots, caterpillars, greyish green long-horned beetles, and cream and brown striped sunflower beetles. Black weevils, brown and white weevils and moth larvae especially tend to damage plant stalks. If sunflower seeds have scars on them or are empty, sunflower moths, sunflower seed weevils or tarnished plant bugs may be to blame.
Most pests that eat sunflower plants cause cosmetic damage to the plant's leaves or stalks but do not kill off entire crops. However, some bugs, like longhorn beetles and sunflower stem weevils cause stalk breakage from their boring. Injury from insects also makes the plants more susceptible to fungal diseases.
Weeding sunflower fields and crop rotation helps prevent severe insect infestations. The University of Minnesota and Kansas State University recommend insecticides to get rid of sunflower beetles and sunflower moths.