Dealing with Aphids on Black-Eyed Susans: Identification and Control

Black-eyed Susans (Rudbeckia) are generally tough, but aphids can quickly colonize the undersides of leaves, forming dense colonies of small, round, black insects that barely move when disturbed. If the bugs scatter rapidly, they may be something else.

Confirm the Plant

Ensure you’re growing Rudbeckia (perennial coneflower) and not an annual sunflower, which is also called black-eyed Susan in some regions. Rudbeckia is the likely host.

Control Options

• Water blast: A strong jet of water under the leaves can dislodge aphids, but it’s labor-intensive and may miss hidden colonies.
• Insecticidal soap: Effective against aphids and gentle on beneficial insects like lady beetles. Apply according to label directions.
• Beneficial insects: Release lady beetles (ladybugs) – they devour aphids rapidly. One gardener eradicated a severe scale infestation on a ficus overnight with lady beetles.

Why Treat?

While aphids rarely kill established Rudbeckia, heavy infestations cause leaf curling, flower distortion, and reduced vigor. You want thriving, blooming plants, not just survivors.

Monitor weekly and act early. A combination of soap sprays and lady beetle releases usually brings aphids under control within days.