What is eating strangler figs on Sanibel?
Recently, Sanibel residents have been reporting a rapid defoliation of strangler fig trees, which have otherwise shown great resilience post Hurricane Ian. The culprit is the caterpillar of the Edwards wasp moth. It is an insect species that is native to Florida and commonly found in the southern region of the state. Due to their annual breeding cycle, the pale yellow to cream colored caterpillars may be found at any time of the year.
Certain types of plants are tied to the lifecycle of butterflies and moths, be it for nectar or larval host plant. In this case, the larval host plant for the caterpillar is exclusively Ficus trees, which includes the native strangler fig. The caterpillars may feed on leaf margins or chew irregularly shaped holes in the leaves.
WHY ARE THEY SO ABUNDANT NOW?
We don’t know for sure. Sanibel usually has plenty of natural predators and Ficus trees on the island that would likely offset the vegetative impacts of the caterpillars. However, the combination of saltwater inundation, wind damage and hurricane debris may have left limited options for the Edwards wasp moth caterpillars to select from, possibly making impacts to the strangler figs more apparent than in normal years. Interestingly, the species was also reported as a problem in the Florida Keys in Monroe County after Hurricane Irma in 2017 (https://blogs.ifas.ufl.edu/monroeco/2018/05/18/whats-eating-my-ficus/).
MY STRANGLER FIG LOOKS DEAD AFTER THE ENCOUNTER WITH THE CATERPILLAR, WHAT SHOULD I DO?
For now, be patient and continue to monitor. As seen with Ian, native vegetation is well adapted to environmental stressors, be it natural disasters or small insects. Mature trees should be able to endure periodic defoliation, and we hope our island’s strangler figs can overcome this latest challenge aided by the onset of summer rains. The strangler fig is one of the most iconic trees on Sanibel and is one of the most important for migratory songbirds and other wildlife.
For questions about stranger figs or the Edwards moth caterpillar, contact Rachel Rainbolt with the city’s Natural Resources Department at 239-472-3700 or Rachel.Rainbolt@mysanibel.com.