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A 37-year study finds that the population of the orange insects visiting Florida has fallen sharply.



Times Staff Writer

Every year thousands of monarch butterflies dance through the air over North Florida, traveling between their winter refuge in Mexico and their regular homes along the U.S. Atlantic coastline. The colorful pageant attracts flocks of tourists who are eager to bear witness to this sprightly migration.

Every year, though, there have been fewer and fewer of the princely insects to see.

A new University of Florida study - at nearly four decades, the longest of its kind - has found that the number of caterpillars and butterflies in North Florida has been declining since 1985.

Since 2005, the numbers have dropped by 80 percent.

'It's alarming,' said associate professor Jaret Daniels, a coauthor of the study.

He pointed out that if a beloved and widely known species such as the monarch can be pushed so easily toward extinction, imagine how much more imperiled are other, less wellknown ones.

'It exemplifies all the issues we're having to deal with in con- servation,' he said.

The scientists involved in the study say the causes of the decline are not entirely clear, but they believe there are two major factors at work.

One is the destruction - by development or agriculture of areas that had been planted with native milkweed, the favorite food of young monarchs. The other is the widespread use of a herbicide called glyphosate, often applied to farmers' fields to kill weeds. One of the weeds it kills is milkweed.

The study was launched 37 years ago by an internationally known monarch expert named Lincoln Brower. He died this summer at age 86, just before the study was published in the Journal of Natural History.

Brower began studying monarchs in the 1950s. He was instrumental in locating the fir trees in Mexico where they spend the winter before heading back for Florida. In their winter home, about 80 to 100 miles west of Mexico City, the trees are thick with the orange insects, and when they flap their wings the sound is like thousands of leaves rustling.


Photos courtesy of Florida Museum of Natural History

Monarch butterflies on their migration north create another generation to finish the trip.

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