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Monarch butterfly population fluttering downward

Monarch butterflies such as this one will be tagged Saturday with a round sticker attached to the wing with information to contact University of Minnesota-Crookston. Herald photo by Jackie Lorentz.

The monarch butterfly, with its distinct orange and black coloring, is one of North America's most recognizable insects.

It's also one that's quickly disappearing.

A recently published study reports the number of monarch butterflies worldwide has been reduced by half. The study, published in the journal Insect Conservation and Diversity, says the use of genetically modified corn and soybeans in the central United States is partly at fault.

Jan Knodel, an entomologist at North Dakota State University in Fargo, said nearly all of the corn and soybeans now being planted have been modified to withstand herbicides, allowing farmers to remove weeds from farmland without damaging crops.

One of these weeds is the milkweed plant. Knodel said milkweed plays host to the monarch's eggs and larva. Without milkweed, the monarch cannot complete its life cycle.

It is estimated that 100 million acres of farmland in the central United States are now milkweed-free because of increased usage of genetically modified crops in the last decade.

Deforestation in Mexico, the butterflies' winter home, is also playing a part in the species' disappearance.

"There are fewer places for them to stay," Knodel said.

During the fall migration, monarchs make a lengthy move to a concentrated area in the Trans-Mexican Volcanic Belt pine-oak forests where they spend the winter. For much of the time, the butterflies hang in heavy clusters on trees. In spring, they head north to lay their eggs.

"Some other species of butterfly get blown up here by the wind from the south," Knodel said. "But they don't go back where they came from."

Local threats

Butterflies also face risks on a local level. Knodel said chemicals used for mosquito spraying can kill the monarch, as well.

"I haven't seen as many this year," she said.

Last August the Herald reported massive numbers of dead butterflies were found after a mosquito spraying in Grand Forks and East Grand Forks.

Residents awoke to find dozens or even hundreds of deceased butterflies, along with other insects, on their lawns and sidewalks.

Butterfly gardens

Knodel recommends planting milkweed for caterpillars and any flowering plant to help the species adapt to a reduction in its habitat.

"You'll be providing them food and shelter on their migration," she said.

Avoid spraying pesticides near the garden as this can kill both caterpillars and adults, Knodel said.

If planting a garden isn't an option, Central Middle School in East Grand Forks has a resident butterfly garden you can visit.

You'll just have to wait a while to see what monarchs there may be this year.

"It's not the right time of year to see them," said Laurie Arnason, a fourth-grade teacher in East Grand Forks and caretaker of the butterfly garden. "We'll probably see more in a few weeks."

The normal monarch migration viewing season for the area spans from Aug. 24 through Sept. 5.

This summer, Arnason and her science club students have collected seven monarch eggs and five caterpillars during their visits to the garden.

A visit Wednesday brought the discovery of another egg.

Last year, Arnason said she found 17 caterpillars among the garden's milkweed. She remembered seeing many more butterflies last year.

This year, she said she ordered monarch larva from Monarch Watch, a conservation group based at the University of Kansas.

Arnason plans to have her students raise these monarchs and release them.

Monarch Watch and other conservation groups also operate butterfly tagging programs.

Small stickers are placed on the monarchs and are used to track the species' migration.

If you find a monarch with a tag, you can contribute to the study by entering the tag information into a database at

McClatchy Tribune contributed to this report.

Reach Jewett at (701) 787-6736; (800) 477-6572, ext. 736; or send email to