By Richard Levine
An article published in the journal Florida Entomologist tells the story of a butterfly that was nearly gone, but is now recovering. In fact, it’s doing so well that some people consider it to be a pest.
Back in 1888, the Atala butterfly was so numerous that it was called “the most conspicuous insect” in South Florida, but half a century later, in the 1950s, it was thought to be “probably extinct.” Fortunately, the butterfly was actually hiding deep in the remaining pine rocklands and tropical hammocks of coastal southeastern Florida, where its host plant still remained.
The Atala butterfly (Eumaeus atala) relies on a plant called coontie (Zamia integrifolia) in the same way that monarch butterflies rely on milkweed species. Atala females lay their eggs on coontie, the only native cycad in North America — and only on coontie (or on other cycads brought to South Florida as ornamental plants) — and after the eggs hatch, the caterpillars munch on the coontie leaves.
Unfortunately for the butterfly, people also like coontie. Native Americans and European settlers harvested the roots as a source of starch that was capable of withstanding the high humidity and temperatures of Florida. Although the coontie plant contains numerous neurotoxins, they are water-soluble and the plant was heavily utilized as a mold-proof harvest. It was exploited to the extent that it was simultaneously sold during the Indian-American Wars to both the Indians and the U.S. Army, and it was also sold to European markets as gourmet flour.
Previously, so much coontie grew along the New River in Fort Lauderdale that the Indians called it the “Coontie Hatchee,” meaning the “the Coontie River.” But by the 1920s, all of the coontie plants within a reasonable distance had been harvested.
The butterfly, of course, went down with the plant.
Luckily, the University of Florida’s McGuire Center for Lepidoptera and Biodiveristy received donated preserved specimens of Atala butterflies, which offered clues about them. The specimens had been collected in pine rockland habitat in southeast Florida (now part of the Everglades National Park), so scientists knew for sure that they once lived there. They also knew that some coontie plants were still growing there.
In 1979, a local naturalist “discovered” an Atala butterfly colony on one of the barrier islands along the coast of Miami, and that’s when the recovery began.
“As far as we know, every extant colony in South Florida originated from that colony,” said Sandy Koi, one of the co-authors. “It is only because of the dedication of scientists and local citizens that the butterfly has recovered to the point that it may be considered a pest in botanical gardens and developments that use the also-recovering coontie plants as ornamental landscaping.”
That’s right. The Atala butterfly was incredibly abundant, then nearly extinct, and now its numbers are high enough to annoy people as the larvae eat their expensive plants to the ground. On the other hand, many individuals and botanical gardens seek out this rare and beautiful butterfly for their gardens, so they plant and grow coontie as Atala food.
“I have been using this fact in order to implement an integrated pest management method,” Sandy said. “Along with dedicated volunteers, we remove the unwanted colonies of both plants and butterfly immature life stages, and install the removed pupae or larvae into the gardens that want to host them.”
In recent years, there’s been a big push in South Florida to plant native ornamentals back into landscapes and gardens. As a result, there are coontie plants all over the southern counties. Now that the host is back in the landscape, the butterfly is back too.
“I have this butterfly in my garden since I grow the host plant,” said Thomas Chouvenc, a researcher at the University of Florida, based in Fort Lauderdale. “It’s a delight to see them fly around. The plants get munched, but they always come back”.
The article, published in Florida Entomologist, also revealed new insights on the unique biology of the Atala butterfly.
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Richard Levine is Communications Program Manager at the Entomological Society of America and editor of the Entomology Today Blog.