Atala: Back From Extinction

 

Atala (Eumaeus atala) on its host plant Coontie (Zamia integrifolia).
Green Cay Wetlands, Palm Beach County, Florida.

The history of the brilliant butterfly Atala (Eumaeus atala) is a story of both a conservation disaster and a triumph.  This bright butterfly is native to southeastern Florida, the Bahamas, Cuba other islands in the West Indies.  But, by 1937 Atalas were extinct in Florida, the victim of habitat destruction and overharvesting of their host plants.  Then, beginning in 1959 scattered specimens were found and in 1979 a population of Atala was discovered in Miami-Dade County.  Since then, Atalas have spread up the east coast of Florida and have even colonized Florida's west coast, a location where they had not been found before. 

Atala larva on Coontie.
Green Cay Wetlands, Palm Beach County, Florida. 

What is this unique butterfly and how did it make such a dramatic comeback?   Atala was named for the  heroine of a 19th century French novella by Chateuabriand.   They have black wings with dazzling blue iridescent spots. The hindwings have large red patches and the abdomen is bright orange.   Atalas will only lay their eggs on cycads and the only naturally occurring cycad in Florida is Coontie (Zamia integrifolia).  The Atala eggs hatch on the Coontie and the bright orange and yellow caterpillars eat the leaves.  The larvae go through several molts and the final larval stage forms the chrysalis.  From this the adult butterfly emerges.  

An Atala caterpillar that has eaten most of a Coontie leaf.
Green Cay Wetlands, Palm Beach County, Florida. 

Atala larva beginning to form a chrysalis.
Green Cay Wetlands, Palm Beach County, Florida. 

Atala chrysalis on Coontie.
Green Cay Wetlands, Palm Beach County, Florida. 

Coontie is native to Florida, southern Georgia and the Bahamas.  Cycads including Coontie have palm-like leaves, but they are gymnosperms more closely related to pines than palms.   Cycads are an ancient lineage that arose before the time of the dinosaurs.  The Jurassic Period is sometimes known as the “Age of Cycads”.  

Coontie is the natural host plant of Atala in Florida.
Ocala National Forest, Florida. 

Coontie roots were used for millennia by native peoples of Florida to produce starch.  But this starch had to be carefully prepared because all parts of the plant contain a toxin called cycasin.  Cycasin is neurotoxic and carcinogenic, but the Atala larvae are able to eat this plant because they are resistant to the toxin.  This chemical protects Atala larvae and adults from most predators.  The bright color pattern of Atala is a warning to birds and lizards not to eat these caterpillars or butterflies. 

In the 1800s when the native people of Florida were removed or driven into the Everglades, American settlers began harvesting Coontie for its starch themselves.  They established factories to make the starch and harvesting drastically reduced the Atala’s only host plant. Development in South Florida also reduced Coontie populations.  One of the reasons the Atala has made a comeback is Coonties are now used as landscape plants.  This native cycad is drought resistant and its toxin makes it unappetizing to most herbivores. Another reason for the surge in Atala populations is other species of cycads are being used for landscaping in South Florida and they too can host the Atala larvae. 

Florida Atalas have made a stunning return.  Atalas are thriving, having gone from extinction in the 1930s to being a common suburban butterfly today, with a some help from people and their plantings.   

Adult Atala.
Green Cay Wetlands, Palm Beach County, Florida.