Most moths are nocturnal and can be colorful additions to our backyards often attracted to lights at night or found on the side of the house in the morning. There are also what are called “day-flying moths” which include the polka-dot wasp moth also known as the oleander moth. This beautiful iridescent, spotted, red-rump moth masks the hidden danger – oleander caterpillars! Oleander caterpillars don’t fool around – they have chewing mouthparts and know how to use them!
First, oleander moths did not always eat oleanders. This native moth used to feed mostly on a rare native plant called the Devil’s Potato found on the east coast of Florida. When oleanders were introduced into Florida in the seventeenth century, oleander moths added this new larval food source to their menu. Since then, oleander moths have also added the desert rose and allamanda to their diet – all in the same family as oleanders.
The life cycle begins when mated female oleander moths search out their food sources and lay egg masses on the underside of leaves. These egg masses can have up to seventy-five eggs. These hatch out and begin to feed as a group more or less skeletonizing leaves. This “group-feeding” behavior changes after a little over eight days when they move on to feed by themselves eating entire leaves. Many individual caterpillars can literally defoliate an oleander plant. While these plants will tend to recover, they are not very ornamental until they have fully regrown. You will not forget what an oleander caterpillar looks like – orange with tuffs of black, non-stinging hairs. Once the caterpillars have matured, they seek out pupating sites where they group together and metamorphize into messy, silk-covered masses.
Many gardeners have suffered under the menace of oleander caterpillars – including me! What would a management plan look like? First, monitor frequently to find either egg masses or infestations of small caterpillars early – also keep an eye out for female moths. These small infestations can be hand-picked and nipped in the butt before they get big and cause serious damage. If large caterpillars get by your scrutiny, simply hand-pick them – the hairs are harmless, and the caterpillars give up without a fight. There are a number of natural predators, parasites, and diseases already in the environment that take out a few caterpillars on your behalf. Organisms such as predatory stinkbugs, parasitic wasps, flies and even fire ants are working for you by suppressing oleander caterpillars. Chemically, perhaps the best material to use is Bacillus thuringiensis, a microbial insecticide found in a number of commercial products available at garden centers – use as per label directions.
Oleander caterpillars are just a fact of life here in Southwest Florida. Frequent monitoring can help reduce the damage caused by these leaf munchers. Don’t give up, just be vigilant! For more information on all types of insect pest solutions, or to ask a question, you can also call the Master Gardener Volunteer Helpdesk on Mondays, Wednesdays, and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Ralph E. Mitchell is the Director/Horticulture Agent for UF/IFAS Extension – Charlotte County. He can be reached at 941-764-4344 or email@example.com. Connect with us on social media. Like us on Facebook @CharlotteCountyExtension and follow us on Instagram @ifascharco.
McAuslane , H. J. (2022) OLEANDER CATERPILLAR, SYNTOMEIDA EPILAIS WALKER (INSECTA: LEPIDOPTERA: ARCTIIDAE). The University of Florida Extension Service, IFAS.
Syntomeida epilais, the polka-dot wasp moth or oleander moth (2023) https://en.wikipedia.org/wiki/Syntomeida_epilais#:~:text=Syntomeida%20epilais%2C%20the%20polka-dot%20wasp%20moth%20or%20oleander,prefer%20Neotropic%20areas%2C%20to%20which%20they%20are%20native.
Wunderlin, R. P., B. F. Hansen, A. R. Franck, and F. B. Essig. 2023. Atlas of Florida Plants (http://florida.plantatlas.usf.edu/). [S. M. Landry and K. N. Campbell (application development), USF Water Institute.] Institute for Systematic Botany, University of South Florida, Tampa.