The Miami Blue, a Butterfly on the Brink

Photo By: Jeffrey Glassberg / North American Butterfly Association

The U.S. Fish and Wildlife Service this week too emergency action to list the Miami blue as an endangered species, recognizing what butterfly-watchers in South Florida have known for decades: This nickel-sized butterfly is on the brink of extinction.

Interesting factoid: The Miami blue caterpillars excrete a honey dew-like substance so delicious to Florida carpenter ants, that the ants act like herdsman raising livestock in order to protect the caterpillars from harm.

Once common throughout South Florida, Miami blues have suffered near-total declines "for reasons that no one knows," in the words of Jeffrey Glassberg, president of the North American Butterfly Association and the author of several books, including most recently, Butterflies of North America ($11 at amazon.com).

By the early 1990s, the decline had been so complete that the Miami blue was known only to inhabit Key Biscayne. In 1992, Hurricane Andrew laid waste to them, and the species was thought lost ... until 1999, when another isolated population was discovered on Bahia Honda Key. The North American Butterfly Association petitioned the federal government in 2000 to list the species as endangered, which it declined to do (after two years of consideration). Florida heeded the call, though, and funded a captive breeding program in hopes that the butterfly could be re-introduced to the wild. As funding ran out, though, so did the population on Bahia Honda Key, Glassberg said, and the species was thought to be extinct. Again.

Almost as quickly, Miami blues reappeared, on the Marquesas Keys, and now that is considered their last refuge on Earth. And this time, the U.S. Fish and Wildlife Service accepted the North American Butterfly Association's petition to list the Miami blue as endangered. How to protect it, though, remains a mystery.

"What really needs to be done is to study the butterfly and find outs what makes it succeed or fail," Glassberg told The Daily Green. "Then you can move on and protect it."

For now the government is avoiding the usual first step in listing a species: Defining its critical habitat. In this case, the Fish and Wildlife Service fears that publishing habitat maps would only invite collectors to capture a rare species for themselves.

The North American Butterfly Association started to encourage butterfly enthusiasts and the public to enjoy butterflies with binoculars, rather than nets and pins. Birding had a similar moment of conscience about a century ago, when the National Audubon Society slowly turned bird hunters into bird watchers.

Today, collecting can take a serious toll on butterflies like the Miami blue, whose numbers are so small that the loss of even a few individuals can be devastating. But the larger reasons for butterfly declines come from habitat loss and pesticide use, Glassberg said, and nowhere are butterfly species more endangered than in South Florida, where species at risk include the Florida leafwing, Bartram's scrub-hairstreak, the Florida white, the Florida purple wing.

"It's not an exaggeration to say that every day in North America, the butterfly population decreased, because every day houses get built, parking lots get built, shopping malls get built," Glassberg said. "A lot of people think if you plow up a meadow and build a shopping mall called The Meadows the butterflies just move someplace else. That's not the case. You've just decreased the world's population of butterflies by that much."

Related: How to Plant a Backyard Butterfly Garden

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