State: Spray may imperil monarch butterfly

TALLAHASSEE -- It is among the most famous and mysterious migrations on earth: Every fall, millions of monarch butterflies flutter southward through North America to Mexico, where they gather so thickly that the paper-thin butterflies can actually break off tree limbs.

Along the route, dozens of towns hold monarch festivals. Thousands of schoolchildren log onto the Internet to chart the butterflies' journey.

But this year, several U.S. butterfly researchers say, the massive monarch migration could face a threat here in the Florida Panhandle, where the state is aerially spraying an insecticide called Dibrom to kill mosquitoes that can carry the West Nile virus.

"It could be devastating," said Karen Oberhauser, an entomologist from the University of Minnesota who has studied monarchs for 17 years. "The migration is a key link in a chain. If something breaks that chain -- like mosquito spray that's going to kill them -- there won't be any monarchs to rebuild the population."

Some monarchs are breeding now in Florida, and more will start migrating through the Panhandle in September and October. State mosquito control officials insist the pesticide dissipates after a few days and should pose little concern. But state wildlife experts are worried enough about the mosquito spray's ecological effects that they've banned spraying on all state parks and federal lands -- including the St. Marks National Wildlife Refuge south of Tallahassee, where the monarchs mass before they head across the Gulf of Mexico.

"The chemicals are broad spectrum and will kill other insects," said Alex Cordero, an environmental specialist with the Florida Department of Environmental Protection. "We have a number of what we call non-target insects on our public lands and we don't really want them to be harmed. They have promised they are not going to spray state or federal lands. But there is still (pesticide) drift, and we all know that."

Florida's other environmental agency -- the Fish and Wildlife Conservation Commission -- also has concerns.

"Any pesticide is lethal and it can kill things. We've voiced our concerns that there are potential side effects to wildlife," said Tim Breault, assistant director of the agency's division of wildlife. "Myself, and a lot of my neighbors, spend a lot of time planting butterfly bushes to attract butterflies. One of the consequences of this spraying is that butterflies could be killed. If I could vote on it, I'd probably vote against it."

The state's Department of Agriculture is in charge of the spraying. DC-3 planes have sprayed four North Florida counties so far, and the state plans to spray four more during the next few weeks. In all, 30 North Florida counties have requested spraying. Some counties also have their own mosquito spraying programs.

The state started loading planes with pesticides after birds, horses and people came down with the West Nile virus. So far, four people -- two in Madison County and one in Jefferson County in North Florida and one in Key West -- have contracted the flu-like virus, but none have died. An elderly woman in Atlanta died of the virus last week. In Okaloosa County, also in the Panhandle, two people died of another mosquito-borne virus, Eastern equine encephalitis.

Some wildlife experts say the state's decision to do massive aerial spraying is overkill, akin to spraying the ocean because sharks have attacked a handful of surfers. And, they say, the spray targets adult mosquitoes that carry the virus, knocking back the population for just a couple of weeks. The spray is highly toxic to bees and fish, and moderately toxic to birds.

"Every bird watcher in Florida ought to be screaming bloody murder," said Chip Taylor, an insect ecologist at the University of Kansas who runs a Web site called Monarch Watch. "They are knocking out much of the insect population that the migrating birds feed on."

"The point of view of many entomologists is that this type of mosquito control is very ineffective," Taylor said. "You get a very temporary knockdown of the existing population, but what you should be doing is going after breeding sites and larvae. There are larvicides out there that have very little impact on other life."

The state official in charge of the spraying, Steve Rutz of the Department of Agriculture, said the state is using an extremely low dose of the pesticide, which should have little effect on humans or wildlife.

"I'm not aware of any data that shows that routine mosquito control activities are decimating the butterflies," Rutz said. "Ideally, you don't use mosquito chemicals at all, but in this situation, we're looking at protecting public health. You can't say 100 percent of the butterflies won't be impacted, but if there are impacts, our experience shows they are very minimal."

Last summer, butterfly researchers were horrified when thousands of monarch butterflies died after mosquito spraying in Gaylord, Minn. Officials used a different chemical than the one that's being used in Florida now. After one night of aerial spraying, children collected hundreds of the dead butterflies in sacks and brought them to the local newspaper. The Minnesota agriculture department later found that the chemical hung in the foggy, humid, night air long enough to kill the monarchs.

"Florida is such a major breeding ground for butterflies," said Sue Halpern, author of a new book on the monarch migration called Four Wings and a Prayer. "The monarchs that are breeding now in Florida, or their offspring, are some of the monarchs that may be migrating in a month."

So far, state planes have sprayed Dibrom in Madison, Jefferson, Wakulla and Liberty counties. They were scheduled to start spraying in Leon County -- home to Florida's capital -- Wednesday.

Rutz said the state could continue spraying for several months, if mosquitoes remain prevalent or if more cases of West Nile virus break out. That could spell even more trouble for monarchs when the migration hits its peak in the fall, researchers say.

Monarchs face threats along their whole journey, which can be as long as 1,500 to 2,000 miles. Farmers clear the milkweed that monarch caterpillars feed on. New, genetically engineered corn can hurt the butterflies. Development wipes out natural lands. In the monarchs' Mexican wintering site, forest clear-cutting is a threat.

The butterflies reproduce along the way, sending waves of successive generations to migrate south. Taylor, of Monarch Watch, said the butterflies end up in about a dozen Mexico sites, all clustered within 50 miles in the mountains.

"When you go in there, you see the trees dripping with monarchs. Then, when the sun hits, tens of thousands take flight and you just hear these whisper of wings," Taylor said. "You look up at these butterflies and you realize all of them came this tremendous distance. What you're looking at is the survivors -- a fraction of the tens of thousands that attempted this trip."

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Lucy Morgan

From the Times state desk