Oleander caterpillars, which are active on some oleanders during summer, can provide a number of landscaping lessons.
The adult moth is striking in appearance. The bluish to purplish moth has white dots on its black wings. The moths resemble wasps as they actively fly in and around oleander shrubs. It’s the orange caterpillars with black spots and black hairs that cause problems for some gardeners.
Caterpillars are the larval stage of butterflies and moths. Lesson number one: In order to enjoy watching butterflies and moths feeding on the nectar of flowers, some of the caterpillars must survive to become the adult butterflies and moths.
Lesson number two: Oleander caterpillars only feed on oleander plants. This relationship between pest and plant is referred to as the key plant, key pest concept. It’s very common. Other examples include St. Augustinegrass and chinch bugs, gardenias and citrus whiteflies, crape myrtles and crape myrtle aphids, azaleas and azalea caterpillars, camellias and tea scale, roses and black spot, pecans and pecan scab, squash and squash vine borers. Oleanders are native to areas of Europe and Asia. Oleander caterpillars benefit by us planting their food source in Florida. Understanding this “key plant, key pest” concept can be very helpful in designing a “low maintenance” landscape.
Lesson number three: Avoid creating a landscape that includes a lot of pest prone plants. For example, when you plant roses, you plant everything that goes with roses, including the time and money required to maintain them. This applies to St. Augustinegrass, pecan trees, squash, oleanders, etc.
Oleander caterpillars can temporarily damage the appearance of oleanders. But they cause no long-term damage for the plant. Lesson number four: The damage is aesthetic. Oleander caterpillars may consume large quantities of leaves; however, if the plant is otherwise healthy, new leaves will be produced and the plant will continue to grow. Long term, there will be no evidence the plant ever had a problem.
If you can’t tolerate the temporary aesthetic damage caused by oleander caterpillars, you can choose to treat the oleander plant with an insecticide to control the caterpillars. You can choose to eliminate the caterpillars’ food source; this involves doing away with the oleander plants. Or, you can choose to tolerate the temporary damage caused by these seasonal pests. If you choose to use an insecticide, always read and follow the label directions and precautions for the product you use.
For more information on oleanders and oleander caterpillars, contact the UF/IFAS Extension Office in your county or visit the below web links.