Mosquito board researches new refuge control method

By Steve Estes

In a year with normal rainfall, the agreement between the Florida Keys Mosquito Control District and the Florida Keys National Wildlife Refuges generally doesn’t stretch far enough for the district to avoid complaints from local residents about the number of biting critters feasting on homeowners inside refuge boundaries.

Under that agreement, the district is allowed to aerial spray over refuge lands nine times per year.

“That’s not very much, particularly if the rainfalls spread themselves out during the rainy season,” said Executive Director Mike Doyle.

District crews try to wait until rainy days stack together to get the most bang for the buck when spraying over refuge lands, but there are still days when the mosquito population, particularly in the more remote sections of Big Pine Key that are populated by intermittent human dwellings, far outnumbers the bodies they have to feed from.

Part of the reason spraying is limited in refuge areas is because the mosquito is actually an integral part of the ecosystem in these parts, says outgoing Refuge Manager Anne Morkill. Killing off all the mosquitoes would cause changes to the life cycle of various plants and animals.

Another reason spraying is limited is because some of the rarest butterflies in the world call some areas of Big Pine home. The chemical used in aerial spraying can kill the butterfly outright “if it’s small or immuno-compromised in some fashion,” says Doyle. “The spray drifts at an angle, both based on the direction of the plane and on the direction of the wind. We can’t make certain that our chemicals will only land on residential areas when we cover large chunks of acreage during an aerial treatment.”

“The last thing we want to do is be part of a process that drives a rare butterfly to extinction,” he added.

Most of the refuge mosquito fighting is done through larvaciding, a labor-intensive, slower method of fighting mosquito swarms in the hot summer months.

Crews attempt to attack mosquito breeding grounds, killing the bugs before they can hatch into biting adults. But that requires a person on the ground, trekking through the backwoods of Big Pine or other remote areas where the refuge is a major landholder, searching out standing water and treating those potential breeding grounds.

To clear residential lots, district field inspectors must visit the homes, search for standing water that serves as breeding grounds and treat those areas.

“That’s labor intensive,” said Doyle.

But there may be a new method on the horizon that will allow the district to cover a lot more ground in residential neighborhoods where spraying is limited.

“We are looking into the possibility of using barrier treatments on Big Pine instead of adultacide spraying or larvaciding,” Doyle said.

The method is particularly effective in areas where large numbers of people gather on a regular basis, such as the county park in Sands Subdivision or Watson Field on Key Deer Blvd.

Right now, said Doyle, the barrier treatment is still very labor intensive.

“It requires a person, with a four-gallon tank on their back, in full protective gear, to edge the property with the chemical from a small-scale sprayer,” said Doyle.

What he wants to do is mount larger sprayers on small trailers pulled by an ATV, allowing the operator to do in 20 minutes what would take all day using a hand sprayer.

But that method won’t work on many residential lots buried in the depths of the refuge because there isn’t enough space to allow for the equipment to pass.

“We need large, open stretches of vegetation to use this method,” said Doyle.

The barrier treatment lays a thick coating of mosquito-killing chemical on the vegetation line at the edge of the property, a coating that mosquitoes won’t cross to get to the succulent humans on the other side.

“We don’t have enough information yet to know if the butterflies will cross the barriers, but we should have those answers in about a year,” said Doyle.

Another issue with the barrier treatments, he said, is that the district would have to have the permission of the refuge to spray the chemical on their vegetation.

“We can’t plaster this stuff across a vegetation line without the refuge telling us it’s okay,” said Doyle. “We know killing mosquitoes, but they know wildlife.”

If the district can get refuge permission, and the permission of property owners where enough space exists to use the equipment, barrier treatments might be a more effective way to treat individual lots than the current larvaciding, he said.

The treatment lasts for about a month, he said, provided there are no massive rainfalls.

“We could cut costs between the amount of aerial spraying we do and the number of people we have to put on the ground to larvacide in Big Pine Key,” said Doyle.

And cutting costs will be on of Doyle’s priorities in the coming years.

The Mosquito Control Board is asking for an 11 percent increase in tax rate this year to cover increased costs associated with killing mosquitoes.

The district is proposing a $14.7 million budget this year, up from $13.1 last year.

And there’s not a lot of wiggle room in that budget right now, says Doyle.

The district needs a $4 million reserve fund, he says.

The board has had to add $750,000 to the system’s personnel accounts to cover accrued sick and annual leave for employees, and must set aside $250,000 for future capital expenditures that won’t be used this year, said Doyle.

Of the remaining $11 million, $6.7 million goes for annual personnel costs and $1.2 million for chemicals. The district expects to spend more than $300,000 this year on fuel, and more than $800,000 on legal fees and permitting costs.

“Personnel is the only non-fixed cost we have right now,” said Doyle.

And he says he’s not a fan of laying off a bunch of people to lower the budget right now.

“I think we can bring the personnel number down through normal attrition over the course of a few years and also by offering buyouts to some people who are close to retirement and willing to take the lump sum in lieu of permanent benefits,” said Doyle.

Property values remained basically flat from last year, according to the Monroe County Property Appraisers Office, but homes with homesteads older than about seven years will see a significant uptick in taxes this year.

Those homes have been protected by the Florida Save Our Homes legislation which limits the taxable assessment to a three percent increase yearly. With the drop in housing values over the last four years, most taxes have remained steady.

“The board may decide to lower that rate at the actual budget hearings next month,” said Doyle. “But for right now, the rate remains the same.”

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