Hibiscus is a large shrub or small tree that produces large, colorful, trumpet-like flowers. The flowers can be as large as 6 inches in diameter, and the tree can grow up to 15 feet tall in areas where it is not threatened by frost. They are very attractive to hummingbirds and butterflies. Like many ornamental landscape plants, hibiscus is also vulnerable to pests like aphids, soft scales, mealybugs and whiteflies. All of these insects exude a sweet substance called honeydew that is very attractive to ants.
Hibiscus and Ants
Ants are attracted to hibiscus flowers because of their nectar-filled blooms. The presence of ants on a hibiscus plant does not always indicate that aphids are also present, and the ants may only be feeding on the nectar.
Ants and Aphids
Ants act as herders for aphids and their eggs. The ants carry the sap-sucking insects and their eggs onto the leaves of the plant and then fight off predatory insects like ladybugs that would otherwise be able to control the aphid population. They do this because they use the honeydew the aphids excrete as a food source.
Always examine a hibiscus for aphids when you see ants; hibiscus is a common aphid host. Examine the undersides of hibiscus plants weekly during the spring and summer for signs of aphids or other insects, even if there are no ants present. Once the aphids establish themselves and begin producing honeydew, the ants will be attracted to the plant and protect this food source.
Controlling ants can help protect hibiscus from aphids, mealybugs and other honeydew-producing pests. Pyrethrin-based insecticides are made from chrysanthemum extracts and are non-toxic to humans and pets. They will, however, kill honeybees and other beneficial insects, so apply them in the evening when there is no risk of harming them. Use horticultural oils, insecticidal soaps or strong jets of water to control aphids.
Aphids not only suck the sap from the hibiscus' foliage, but they are known transmitters of plant diseases. The honeydew also creates the ideal conditions for the development of black sooty mold. The mold covers the foliage, eventually making it impossible for the plant to photosynthesize.