Nearly 60 million sterile New World screwworm flies have been released in the Lower Keys and Marathon, but all it takes is one fertile fly to kill a Key deer.
U.S. Department of Agriculture officials said Friday their release of sterile screwworm flies to mate with wild flies since October has been a success in driving down the number of wild flies that create parasitic larvae in the deer. The sterile flies result in fewer flies because offspring can’t hatch.
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Still, having to euthanize endangered Key deer this late in the game is normal, officials say.
“It’s not unexpected at all,” USDA public information officer Tanya Espinosa said about an infected deer euthanized Dec. 11. “This is pretty typical screwworm behavior, so we fully expected to find one or two more positives.”
The deer was found on Munson Island, southwest of Big Pine Key. “We collected samples and the results came back Tuesday,” Espinosa said.
Until then, officers hadn’t euthanized a Key deer, found only in the Florida Keys, since Nov. 15. The number of dead deer due to the worms that eat away at living tissue since early July is now 133. The herd is now estimated at about 875 deer, which stand just three feet tall and are found only in the Keys.
Screwworm flies lay their eggs in the wounds of injured animals. The larvae hatches and then feeds on the wound, basically eating the deer live.
The rate of deaths has also been slowing down because doramectin, an antiparasitic medicine that serves as a preventive measure and treatment for screwworm, has been given to deer since mid-October.
As of Friday, 10,560 doses had been administered to the deer. Included are 3,302 doses for which deer have self-medicated at 21 stations where they access food by rubbing up against rollers soaked in the medicine.
Thousands of pet owners traveling out of the Florida Keys have been stopping at a roadside checkpoint in Key Largo where federal officials examine their pets for New World screwworm. So far, no cases have been found in nearly 10,000 pets leaving the Keys since the 24-hour northbound checkpoint opened in early October.
The screwworm fly is not widely present in the United States, but it is found in most South American countries and in five countries in the Caribbean.
Katie Atkins: 305-440-3219