Monarchs Scarce This Year

FILE- In this Aug. 13, 2012 file photo, a monarch butterfly perches on a tree branch in Montpelier, Vt. It's been difficult to spot a monarch butterfly in Vermont in summer 2013. Conservation biologist Kent McFarland with the Vermont Center for Ecosystems says difficult weather systems in the last two years have contributed to problems for the monarchs. Agricultural practices also have reduced their breeding habitat. (AP Photo/Toby Talbot)

FILE- In this Aug. 13, 2012 file photo, a monarch butterfly perches on a tree branch in Montpelier, Vt. It's been difficult to spot a monarch butterfly in Vermont in summer 2013. Conservation biologist Kent McFarland with the Vermont Center for Ecosystems says difficult weather systems in the last two years have contributed to problems for the monarchs. Agricultural practices also have reduced their breeding habitat. (AP Photo/Toby Talbot)

Colchester, Vt. (ap) — It’s been difficult to spot a monarch butterfly this summer in Vermont.

Conservation biologist Kent McFarland, with the Vermont Center for Ecosystems, told Vermont Public Radio that difficult weather systems in the last two years have contributed to problems for the monarchs. Agricultural practices also have reduced their breeding habitat.

McFarland said the monarch population is measured in the number of acres they cover in their densely packed winter habitat in central Mexico.

He said there’s been a steady decline in numbers since 1996, from 15 acres of forest down to three last winter. McFarland said that represents a drop from about 1 billion butterflies down to 60 million in 15 to 18 years.

The butterflies migrate north from Mexico all summer, but their numbers have not rebounded.