Agencies seeking spraying agreementBy Steve Estes
The National Key Deer Refuge and Florida Keys Mosquito Control District recently kicked off what both hope will be the process that leads to a long-term permitting solution for killing adult mosquitoes on Big Pine Key.
“What we want to do is get away from the need to permit mosquito control each year and develop a long-term management plan for mosquito control on the refuge that allows us to go five or more years,” said Refuge Manager Nancy Finley. “Planning on both sides will be better if we have a long-term basis from which to operate.”
Because killing mosquitoes has the potential to harm two butterfly species that are soon to be listed as endangered on Big Pine Key, or the potential to impact the habitat used by those butterflies, primarily croton, the district requires a permit from the US Fish and Wildlife Service, the agency that ultimately has oversight authority for the Key Deer refuge.
The most recent permit expired in June 2013 and the district has done no adult bug spraying on Big Pine Key since then. Very little was done prior to that either, as the current yearly permit contained some tight guidelines about spraying in areas where the insecticide used could drift into those places considered valuable habitat for the Florida Leafwing and the Bartram’s Scrub Hairstreak butterflies.
Basically, large-scale aerial missions over Big Pine Key have been all but eliminated for the last couple of years, and truck spraying in neighborhoods has been curtailed where refuge lands intersect with private lands in close proximity to potential butterfly habitat.
According to District Executive Director Mike Doyle, truck operators were forced to turn the spray nozzles on for residential areas where no habitat area might exist, and then turn them off in any areas where drift would hit refuge lands.
“The cost-effectiveness of that practice made it almost impossible to adequately conduct spraying missions in neighborhoods where refuge lands outnumbered private property parcels,” said Doyle.
The district has been able to continue its larvaciding program both on Big Pine Key, No Name Key and the outlying islands, which is why the mosquito problem hasn’t been worse than it is, he said.
Before 2003, most of the district’s mosquito control efforts were geared at killing adult bugs, which required a lot of spray missions during the hot months of mosquito activity, essentially the hotter, wetter months of the year.
“Before the implementation of the intensified larvaciding program, most of the adults mosquitoes actually emerged and were killed using large-scale spraying missions, either aerially or by low-volume trucks,” said Doyle.
Up until 2008, most of the streets on Big Pine Key and No Name Key could be routinely sprayed with adult insecticide.
Then came the first of the studies showing that the butterfly, an insect, could fall prey to the chemical in use by the district and the large-scale spraying efforts were cut back and larvaciding was intensified.
“In a typical July, we treat about 250 football fields worth of land daily by larvaciding,” said Doyle. “We estimate that we kill 94.7 billion mosquitoes yearly, or about 1.3 million per person in Monroe County.”
Doyle said that larvaciding eradicates about 90 percent of the potential mosquitoes that would otherwise attack Big Pine area residents, “But even 10 percent is still a lot of mosquitoes. That’s why some form of adulticiding is still necessary.”
“The only way to be fair to both the endangered species the refuge is charged to protect and the humans who live in close proximity is for the refuge and district to work together to devise a mutually beneficial management plan over the long term for mosquito control,” said Finley.
Environmental groups won a court battle that claimed the refuge was moving too slowly in implementing protections for the two endangered butterfly species, and the courts ruled that the listings for the two had to be complete by 2018.
“The service published critical habitat areas for the butterflies on Aug. 15, 2013, and after that we were required to initiate a consultation that had to include mosquito control because it is a use on the refuge,” said Finley.
Finley says that right now the refuge has no record of the Florida Leafwing on Big Pine Key, and that the levels of the Bartram’s Scrub have sunk to historic lows.
“When the district sprays for mosquitoes, the chemical drift also kills the butterfly larvae. That is what we’re trying to minimize,” said Finley.
Mosquito Control Commissioner Bill Shaw says he believes that more study is needed to determine the level of impact the district’s activities have on the butterfly population.
“There is anecdotal evidence that the less we spray for mosquitoes, the smaller the population of the butterfly becomes. That is a study that needs to be done. We may be working in reverse,” said Shaw.
Refuge officials, however, say that the studies showing deaths of butterfly larvae from mosquito spray are accepted by USFWS.
“It is happening right now on the refuge and we must mitigate for it,” said Finley.
She agreed that one of the strategies that may arise from a long-term management plan will be further study of the spray-to-population-trend evidence, but that at the moment no one is paying for that study, “And it is something that is a year’s long effort. We have to have management actions in place well before we could verify the results of that study,” said Finley.
The recent meetings were held to gather both agency and public input on potential management strategies for mosquito control on the refuge. From those comments, the refuge staff will develop a draft environmental assessment.
That, says Finley, should be completed by late January 2014.
The draft will be placed for public and agency comment for 30 days, any revisions will be made, and Finely said they hope to have a new plan in place by this spring that will allow limited adult spraying before the start of the next high season for mosquito breeding.
If the plan is delayed, Mosquito Control Commissioner Jack Bridges said that the results could become skewed as private individuals begin their own mosquito control campaigns with commercially available insecticides that aren’t as environmentally friendly as what the district uses.
“That is something we have considered that could cause harm to the species and habitat,” said Finley. “It’s something we’ll have to analyze inside the EA process.”
The environmentally friendly nature of the chemicals the district uses are part of the problem faced by both sides, says Doyle.
“We’re placing larvacide pellets anywhere we find breeding areas,” said Doyle. “But the weather can lessen their effectiveness if we get follow on rains that don’t allow us to treat in a timely fashion.”
Doyle said the window to treat following a breeding event is about three days. After that, the mosquito larvae have reached the stage where they don’t ingest the pellets and they turn to adults.
Finley said that although insecticides are one of the leading cause of the demise of the butterfly and the croton habitat that supports them, there are other reasons that must be addressed in the EA.
“We are losing croton habitat. We have to incorporate prescribed burning and mechanical rehabilitation to enhance the croton stands we do have,” she said.
The latter might be one area where the two agencies can work solidly together, says Shaw.
“We need to start looking at programs that will mitigate croton recovery to areas where we will never spray, essentially moving the butterfly out of our path,” said Shaw.
He and Bridges agreed that the district would have to conduct drift analysis for its spray missions as part of the EA process.
“But we also need to be looking at the past research, and the need for future research on the actual effect of our spray on crotons and the butterfly. The downward trend linked to less spraying may well be more than coincidence,” he said.
Doyle said that the district is planning to deploy drones to search for potential breeding sites that human inspectors can’t reach effectively, and follow those sightings up with helicopter missions to spread larvacide.
“We can start to do a better job with new technology in finding where the mosquito starts and killing them before they reach adult, but the program will never be as good as we want it to be if we don’t work together to find a suitable adulticide program,” said Doyle.
Local residents are asked to speak out about the mosquito management plan either through the local refuge office of through the mosquito control district offices. Both agencies have local internet sites where comments can be posted as well.