Bright colors of the Atala butterfly advertise a nasty meal and warn predators not to take a bite.
Hatched eggs of the Atala festoon the coontie’s cones.
With the arrival of Old Man Winter in much of the United States, it’s time for Bug of the Week to get out of town and head south to visit bugs in warm places. Our first stop on this global sojourn is Coral Gables in southeastern Florida, home of the coontie and the gorgeous Atala butterfly. Coontie is the local name for the curious plant, Zamia pumila, a native of the Sunshine State. Zamia belongs to a large group of ancient plants known as cycads that harken back to the time of dinosaurs. After millions of years battling herbivores, Zamia and other cycads evolved toxic compounds known as azoglucosides to defend themselves from hungry hordes intent on eating their leaves.
As the Atala caterpillar feeds, it stores noxious chemicals from the leaves of the coontie.
Ah, but one denizen of the coontie has bested its chemical arsenal. Larvae of the Atala butterfly eat the leaves of the toxic cycad and store the noxious compounds which, in turn, are passed along to the adult butterfly. Atala caterpillars are said to have an unpleasant odor and the chrysalis is protected by small drops of nasty fluid. The spectacular coloration of the caterpillar and butterfly serve as a warning to predators like hungry birds not to risk an attack lest they suffer the consequences of a toxic meal in much the same way that the orange and black coloration of monarch butterflies and other milkweed feeders serves as a warning to their predators. Aposematic or warning coloration is the name of this game and it is widely practiced by many species of butterflies, moths, beetles, flies, and stinging insects such as bees, wasps, and hornets.
Widespread planting of cycads in landscapes support the return of the Atala in Florida.
In a time when urbanization threatens many native insect species, there is some good news for the Atala butterfly in Florida. The widespread planting of the beautiful coontie and other cycads in residential landscapes provides a bounty of hosts for this relatively rare butterfly and some reports indicate that this urban adapter has become more abundant in recent years.
After consuming leaves of coontie, Atala caterpillars move to non-host plants nearby. This tactic may foil predators and parasitoids searching leaves of coontie for prey while juveniles are relatively helpless in the chrysalis stage.
References
We thank the intrepid Dr. Shrewsbury for discovering the subjects for this episode of Bug of the Week. The remarkable references “Caterpillars of Eastern North America” by David Wagner; “Cycads: their evolution, toxins, herbivores and insect pollinators” by Dietrich Schneider, Michael Wink, Frank Sporer and Philip Louniboshearty; and “Florida Coonties and Atala Butterflies” by Daniel F. Culbert were used to prepare this story. A visit to the Fairchild Botanical Garden in Coral Gables may reward you with an encounter with the gorgeous Atala butterfly and its larvae.