Hoping to establish a new colony of the rare Miami blue butterfly, scientists have released 500 caterpillars into Everglades and Biscayne national parks.

Dressed in long pants and thick mosquito jackets in 90-degree weather, University of Florida researchers picked through the Everglades National Park last week, placing hundreds of one of the rarest butterflies in North America back into the wild.

Their mission: to reintroduce the Miami blue butterfly to Miami-Dade County and help save it from extinction.

About 500 minuscule black caterpillars were carefully placed on budding nickerbean plants, a vine-like shrub that the Miami blue eats, which grow in Everglades and Biscayne national parks. During their time in the laboratory, the caterpillars were bred on nickerbean plants in the hopes they would believe they were in a familiar environment when they moved.

REINTRODUCTION

Attempts to reintroduce a species formerly held in captivity to the wild can fail.

''When you breed things in a small population, they lose some of their wild characteristics,'' said John Capinera, chairman of the Entomology Department at UF's Institute of Food and Agricultural Sciences.

Four locations in the parks were chosen -- locations far from areas where toxic pesticides are sprayed, humans have easy access and predators prowl.

''There are a lot of hungry critters out there,'' Capinera said.

Each caterpillar was strategically placed a few feet away from the others to avoid competition for food in their new home. The reintroduction process took about 16 hours.

''We handled them like little babies, with tender, loving care,'' said Thomas Emmel, director of the university's McGuire Center for Lepidoptera Research. ``They crawled onto the vine and happily started eating.''

''They're on their own now,'' added Capinera.

In 18 to 28 days, researchers hope they will bloom into the brilliantly hued butterflies that were said to be only a storm away from extinction four years ago.

Their aim is to establish a new colony of the endangered Miami Blue. Thought to be extinct, the butterflies were discovered in 1999 in Bahia Honda in the Florida Keys.

THE WAITING PERIOD

The reintroduction of the Miami blue to the wild culminates a long period of research and evaluation.

For the past 15 months, Jaret Daniels, assistant director of the McGuire Center, and his crew bred and harvested 9,000 adult butterflies, as he waited for authorization to reintroduce the butterflies to the wild.

''It's exciting for us because we're seeing all that hard work come into fruition,'' said Daniels, director of the project.

Once an insect that proliferated in Southern Florida, its population began to decline in the 1980s due to the heavy spraying of pesticides, the disappearance of a species of ant that had protected them from predators and urban development.

''The problem with most wildlife is disturbance with people,'' Capinera said. ``We don't share our environment very well with other animals.''

When the butterflies were rediscovered in 1999, they were in a colony of fewer than 50.

In 2002, the state issued an emergency endangered species protection order for the Miami blue. Under the act, it is a third-degree felony to kill or catch the Miami blue butterfly. Violators can get up to five years behind bars and a $5,000 fine.

The yearlong deliberations that resulted in the reintroduction of Miami blues to the national parks involved the U.S. Fish and Wildlife Service, the Florida Fish and Wildlife Conservation Commission, the Florida State Park system, the Monroe County Mosquito Control and the Florida Department of Environmental Protection.

''It takes a long time for all these agencies to agree on the place of choice to release them to ensure their protection where scientists can monitor them,'' said Emmel. ``We had to work around the government tape and under the Endangered Species Act.

FUTURE PROJECTS

Emmel said he hopes to look at reestablishing the Miami blue elsewhere in Miami-Dade and Monroe counties in six months.

Suitable habitats with the right kind of food plants still exist from Orlando to Key West, but urban development eliminates many options for the butterfly population.

''Right now we're targeting the most remote locations first, where it's protected from some dangers of human development and poaching,'' said Daniels.

The exact location of the Miami blue reintroduction sites will be kept secret to protect them from collectors. While visitors have access to the parks, there will be no notice that they are in the vicinity of the Miami blue.

''If they see one, that's fortunate for them,'' said Rick Cook, a spokesman for Everglades National Park.

PRIMARY CAUSE

Once the butterflies reestablish themselves in the national parks, researchers hope to finally determine the primary cause of the Miami blue's near-extinction.

''The fact that it disappeared on such a broad range suggests that while the pesticides may have contributed, it may not be the singular cause,'' Emmel said.

``The butterfly may tell us that there is some fundamental change in the environment that is affecting us.''