Horse Gulch Blog

Watchdogging for the greater Durango area

23 Jul 2016

Animas Mosquito Control District now focusing more on larvicides versus spraying to abate

Posted by Adam Howell


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Beekeepers and their honey bees in La Plata County have one more reason to sleep well at night: they won’t be a casualty of spraying that’s done for mosquito abatement on the Animas Mosquito Control District.

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Animas Mosquito Control District’s Field Technician, Terry Eshelman dips a cup into a pool of standing water to check for mosquito larvae. Photo courtesy of the AMCD.

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Animas Mosquito Control District’s Field Technician Terry Eshelman checks a dipping cup for mosquito larvae. Photo courtesy of the AMCD.

That’s because bees will have one less airborne neurotoxin to die from, as the Animas Mosquito Control District (AMCD) has progressed towards a more wholistic approach to mosquito control that leverages with more organic larvicides, instead of spraying the adulticide of Permethrin-laced mineral oil during the day.

AMCD Manager Joe Kuefler said that in 2014 the District had a change of philosophy in the way it operates. He said that his employees are no longer spraying a Permethrin-spiked mineral oil insecticide mixture during the day, a known neurotoxin to both mosquitoes and honey bees.

Now days, AMCD only occasionally sprays Permethrin at night when bees are sleeping, said Kuefler.

This change in operational tactics came following the findings of a 2014 study by field technicians working for a mosquito abatement district in Salt Lake City, which suggested that Permethrin had a deadly impact on bees that were tested after being exposed to wet Permethrin, said Kuefler. The change also came after the last General Manager for the District, Sterling Schaaf retired in 2013.

An EPA fact sheet says that Permethrin toxicity data show that the compound is highly toxic to honeybees, as well as other beneficial insects.

Beekeeper Valerie West has three hives in the valley near Dalton Ranch on property belonging to someone else.

“It’s reassuring that they’ve got a new general manager, and that they’re going to be changing their practices,” said West. “It’s a win for the beekeepers and the honeybees.”

Kuefler said that the District would honor a request to be on the no-spray list from beekeepers such as West who have hives on property in the District that are not owned by the beekeepers themselves.

“I would do that for any beekeeper,” said Kuefler.

Also, as a more effective, focused and environmentally-safe practice that they’ve put more emphasis on in their daily operations is the targeting of mosquito larvae with an organic larvicide called Natular.

Last year, the District spent around $250,000 dollars on Natular. Field technicians for the District spend lots of their time treating standing bodies of water with Natular briquettes or granules. The technicians locate and record mosquito breeding habitat sites on a GPS system designed for this purpose, said Kuefler.

Effects of Spinosad (in Natular) on honey bees

Beekeepers concerned for their honey bee’s drinking water, yet thankful

Beekeepers in La Plata County who I asked about mosquito abatement for this story had mixed feelings.

Brad Milligin, of Milligin Honey Farms, is a commercial beekeeper with hives in south La Plata County. His business occasionally supplies honey to Honeyville.

For Milligin, who’s hives are technically on the Florida Mesa Mosquito Control District, his concern about mosquito spraying is minimal, he said, because his hives live on drier land where the District would not want to spray anyways.

Several hobbyist beekeepers with hives in the Animas Valley were concerned about the effect of Permethrin/mineral oil on their bee populations, however, and praised the Animas Mosquito Control District for their commitment to stop spraying during the day.

In the Animas Valley at the south end of County Road 250, hobbyist beekeeper Tina Sebestyen has two healthy colonies this year, which she will be treating for mites, she said.

Sebestyen, who is the president of the Four Corners Beekeepers Association said that most of beekeepers at the south end of County Road 250 had their hives die off last year.

“My bees are right against the road so the spraying was what I was concerned about,” said Sebestyen.

Sebestyen is skeptical of the District’s use of Natular, a product certified by the Organic Materials Review Institute for use in and around crops that are certified as organic.

“Organic doesn’t mean not deadly, though. Right,” said Sebestyen. “I definitely don’t want to make enemies with the guys at the mosquito district. For sure. But something else I heard anecdotally, starting maybe two years ago was that they were going on people’s private property and treating their ponds with their larvacide, which supposedly doesn’t kill bees. But, I don’t know, we’ve been hearing this from the manufacturers of all those insecticides. ‘It doesn’t kill bees.’ Right. They all say that about Weed and Feed. They say that Round Up doesn’t kill bees. Well yes, it does.”

“I can’t say for sure that this larvicide does or does not kill bees,” said Sebestyen. “but I can say that we sure lose a lot of bees where they are into mosquito control.”

Hobbyist beekeeper Valerie West also praised the AMCD’s commitment not to spray during the day, but had concerns with their use of larvicides.

“I would like more information about what they’re putting in the water to target the larvae, if that would be harmful to the bees,” said West. “Because the bees will be drinking the water, as well.”

West hoped that the larvicide would cease the District’s need to spray anymore.

The District’s website says that the larvicide is a naturally occurring bacteria that has no bioaccumulation or toxicity to the environment.

AMCD’s General Manager Joe Kuefler, says that there is nothing on the label that relates to bees drinking from water treated with Natular.

“We only treat water that tends to produce mosquito larvae, which certainly leaves a lot of untreated water available in the Animas valley.” said Kuefler. “I think that if I were a beekeeper I would keep a water source close to the hive that the bees would be aware of for their use. If they dump and replace the water twice a week they will not produce mosquito larvae in that water.”

A Material Safety Data Sheet for Natular says that for spinosad, in-vitro and animal mutagenicity studies were negative. Another MSDS sheet for Natular XRT is at this link.

Independent water analysis where mosquito abatement products are used

Every year, the Animas Mosquito Control District contracts Wright Water Engineers, Inc. to test the water quality where they target mosquitoes both before and after they use abatement products to determine if the chemicals remain there long enough to impact other biological organisms.

“With the Permethrin one, all four tests, we’ve never shown a trace,” said Kuefler.

Wrightwater tests for spinosin–the active ingredient in Natular–in the soil and water. Spinosin is a bacteria with a half-life of two days that breaks down in soil, said Kuefler.

“The spinosin product has come up in a couple of places,” said Kuefler. “But it’s where we still have briquettes left, so they’re still emitting spinosin (180 wet days).”

Spinosin is toxic to invertebrates, so the District uses Altosid in the drains, instead.

“We still would like to know if we’re ending up with any Altosid in the river, and so at all sites we tested that this year and came up zero,” said Kuefler.

When District personnel visit private property

With the District encompassing around a 48 square miles from La Posta Road to the south, Edgemont Ranch and Farmington Hill to the east, Wildcat Canyon Road to the west, and Baker’s Bridge to the north, their $685,000 budget that’s funded by taxpayers keeps them busy.

Animas Mosquito Control District flyerWhenever AMCD Field Technicians visit a private property to treat mosquito habitats, if nobody is home they will leave a flier that explains who they are, what they do, and what they did or wanted to do on the property.

Status of wildlife, and disease outbreaks in La Plata County

Since the AMCD was formed in 1960, Kuefler credits the lower death rate of frogs, baby birds, turtles and other wildlife to the change in tactics used to treat mosquitoes. Specifically, less mosquitoes are killing baby birds, and less frogs and turtles are dying in La Plata County because the District is no longer dumping diesel fuel into standing water as a tactic to kill mosquitoes.

The District stopped using diesel fuel for mosquito abatement in 1995, Kuefler said.

For humans, Kuefler credits the comfortable outdoor environment and limited reports of West Nile Virus in the county to the District’s successes at controlling mosquito populations.

This year, there have been no new cases of West Nile Virus confirmed in La Plata County, according to San Juan Basin Health Department’s Assessment, Planning and Communication’s Director Claire Ninde. In 2015 the county had one confirmed case, in 2014 there were zero confirmed cases, in 2013 there was one case, and in 2012 there were five confirmed cases, with one case resulting in death.

There has never been a positive test for Zika Virus in La Plata County, said Ninde.

Quick stats on the neighboring Florida Mesa Mosquito Control District

The following facts were provided by Kay DeLuzio, the Manager of the Florida Mesa Mosquito Control District:

  • Sprays Permethrin/mineral oil by request only.
  • Has a no-spray list.
  • Sprays early in the morning at 4:00, 5:00 or 5:30 a.m..
  • Does not spray near known beehives.
  • Uses Altosid as a larvicide.
  • Has a $270,000 dollar budget for 2016.
  • No longer sprays Melathion.

Residents of southern La Plata County who wish to be on the no-spray list for the Florida Mesa Mosquito Control District should call (970)259-1652.

Beekeepers or anyone else living in the boundaries of the Animas Mosquito Control District who have questions, or would like to request the services of the District, either for spraying, or to be added to the no-spray list should call them at (970)247-1483.

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