News Release
Southeast Region


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U.S. Fish and Wildlife Service and Partners in the Imperiled Butterfly Working Group Conclude Florida Zestos and Rockland Grass Skipper Butterflies are Likely Extinct

June 13, 2013


Two brown and yellow butterflies

Zestos skipper. Photo: Marc C. and Maria Minno

Three brown and yellow butterflies

Rockland grass skipper. Photo: Marc C. and Maria Minno


Atlanta, GA – Following six years of comprehensive survey efforts in southern Florida, the U.S. Fish and Wildlife Service (Service) and its partners in the Imperiled Butterflies of Florida Working Group (IBWG) believe that two butterflies, the Zestos (Epargyreus zestos oberon) and rockland grass (Hesperia meskei pinocayo) skippers, are likely extinct.

These butterflies were historically found only in south Florida. In recent years, butterfly scientists and volunteers have surveyed extensively to determine the status of the Zestos and rockland grass skippers, and other imperiled butterflies. Surveys included areas they were previously found, as well as new areas, primarily public conservation lands throughout southern Florida and the Florida Keys.

The Zestos skipper was last observed at the Key West Tropical Forest and Botanical Garden on Stock Island on January 24, 2004. This butterfly had not been observed on mainland Florida in several decades.  The rockland grass skipper was last observed at Everglades National Park in 2000, with an additional population occurring on Big Pine Key until 1999.  

The Zestos skipper occurs commonly throughout the Bahamas and eastern Antilles.  Based on this information, the Zestos skipper was not considered imperiled, globally, and therefore the butterfly was never considered for listing as endangered in the United States.  It was only recently discovered that the Zestos skipper in Florida was in fact a distinct subspecies, found nowhere else. Before conservation agencies could move to protect it, it was gone.  Similarly, the rockland grass skipper was thought to be extinct in the 1980s.  However, it was briefly rediscovered on Big Pine Key in 1999, but disappeared again before recovery actions could be implemented.  

Leopoldo Miranda, the Assistant Regional Director for Ecological Services in the Service's Southeast Region, said the two butterfly species are examples of missed opportunities for protection under the Endangered Species Act. "We are working closely with our state, federal and private partners -- such as the IBWG -- to assess which species need federal protection, and which ones need some proactive, pre-listing conservation measures to thrive."

Service scientists believe the main cause of decline and disappearance of butterflies in southern Florida is loss, modification and fragmentation, and in some instances inconsistent management, of the natural habitats that butterflies and their larval hostplants depend on. Other possible factors include: exotic predatory ants, small population size, poaching, use of pesticides for mosquito control and the influence of climate change.

Scientists also believe the pattern of the disappearance in the Zestos skipper is similar to that of the now critically endangered Miami Blue butterfly. Climate change is an acute threat to the Miami blue, as all sites within Key West National Wildlife Refuge known to currently support Miami blues appear to be losing habitat and hostplants due to the effects of sea level rise.  The Service has funded  surveys and research of Miami blue populations within Key West National Wildlife Refuge.  In the near future, the Service, along with IBWG members will develop a recovery plan for the Miami blue.  

In an attempt to galvanize butterfly conservation efforts in southern Florida, the Florida Fish and Wildlife Conservation Commission (FWC), the Service, the National Park Service, the North American Butterfly Association, as well as a number of other agencies and organizations formed the IBWG.  The group meets quarterly to address butterfly-related issues in south Florida.  In addition, IBWG maintains a SharePoint with the latest information on butterfly conservation activities throughout southern Florida.  The SharePoint can be visited at:

“We greatly appreciate the efforts of the IBWG,” said Larry Williams, the Service’s Florida State Supervisor for Ecological Services.  “We’re saddened by the loss of the Zestos and rockland grass skippers and hope their loss serves as a wake-up call that we really need to intensify our efforts to save other imperiled butterflies in South Florida.”

Recent efforts of the IBWG include monitoring and conservation of the federally endangered Schaus swallowtail and Miami blue butterflies in the Florida Keys.  Since 2011, IBWG members have monitored Schaus swallowtail populations and initiated major restoration efforts within Biscayne National Park in order to increase availability of the butterfly’s habitat and larval hostplants. These efforts may also include captive rearing and reintroduction, if needed, to help recover the swallowtail.

A recent state wildlife grant by the FWC to the Florida Natural Areas Inventory involved members of the North American Butterfly Association as citizen scientists to survey and monitor  populations  of other imperiled south Florida butterfly species.  Plans are being made to continue these monitoring efforts after the grant period ends in hopes of taking proactive steps for protecting these other south Florida butterfly species before the need to consider federally listing them.

“The FWC will continue facilitating the IBWG’s collaborative efforts, while promoting awareness for butterfly conservation, the habitats that sustain them, and the roles they play as an indicator species in the larger environment,” FWC wildlife biologist Mary Truglio said.

The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. For more information on our work and the people who make it happen, visit  Connect with us on Facebook at, follow our tweets at, watch our YouTube Channel at, and download photos from our Flickr page at


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Last updated: February 19, 2014