Sunflowers & Pests

Longhorned Beetle

• The longhorned beetle has an ashy, grayish color and exceptionally long antenna that are striped in black and gray. They can cause sunflower stalks to break by burrowing into them and girdling the interior walls. This basically means they encircle the inner walls of the stalk, scooping out a ring from plant tissue. Tunnels are then packed with frass and the longhorned beetle settles down to wait out the winter. This beetle is difficult to discover because it does its damage on the inside of the stalk. Larvae make their way to the stalk from the petioles, where eggs are laid. If you see eggs or adults laying them on the petioles or signs of the stalk weakening or bending, you may have a problem with the longhorned beetle. In this case an insecticide will not work because of the long interval of time over which these beetles emerge from their lodgings after winter. Waiting longer to plant (midsummer) and harvesting in winter may prevent this sunflower infestation, but once the longhorned beetle has already settled in, the best option is to harvest immediately.

Sunflower Beetle

• Identifying adult sunflower beetles is relatively easy. The covers on their wings are white with brown or black stripes running from front to back. These beetles can cause a great deal of damage if left unchecked. The larvae eat the plant's leaves, and in large enough numbers, can completely strip the sunflower of almost all of its leaves. Control methods include insecticides and waiting longer to plant (midsummer).

Sunflower Moth

• The sunflower moth is small and gray, with its wings held tightly to its body. Eggs are deposited inside the central, seed-bearing disc. While this moth, from its larval to adult stage, can be difficult to identify, the damage caused by sunflower infestation is unmistakable. Larvae leave behind a gossamer-like webbing over the face of the sunflower. When larvae feed on the plant they are not only causing immediate damage, they are also opening the door for potential problems like Rhizopus infection, which can cause the sunflower to decay. Treatment includes preventative pesticides, planting later (late June or early July, rather than spring), or using pheromone traps. Pheromone traps attract and capture male sunflower moths, and while they are an option, they typically do not trap a high number of these moths.

Red Sunflower Seed Weevil

• The red sunflower seed weevil is small with a reddish color. Adults eat pollen and inject eggs into sunflower seeds. Aside from spotting adults, the most obvious sign of the presence of this weevil is a small hole at the top of seeds where larvae have burrowed out. An insecticide can be purchased to control and eliminate the red sunflower seed weevil, or you can consider planting at an earlier spring date. Planting earlier is effective because these weevils do not tend to emerge until a later date, but be aware that planting early to avoid the red sunflower seed weevil will open you up to a host of other pests that can be avoided by planting late.

Painted Lady Caterpillar

• The painted lady caterpillar is among the most common pests of sunflowers. It is greenish in color and is covered in thorn-like bristles. It feeds on the leaves of the sunflower plant and can defoliate it if not treated. Like most harmful insects in sunflowers, the painted lady caterpillar can easily be controlled with scouting and the application of insecticide. First you'll want to determine just how much damage it is doing. Determine the percentage of defoliation by selecting sample plants among your sunflower population. To give you an idea of the number you'll want to check, in a large population about 20 plants in five different sections should be examined. Adjust accordingly for a smaller population. Based on the percentage of defoliation, you should be able to determine the appropriate insecticide for you by looking online or asking a professional.