OTTUMWA — If you enjoy watching the migration of the monarch butterfly, you might be out of luck.
Nature researchers say even everyday butterfly watchers are noticing a massive decrease in the number of monarchs they see.
Alicia Houk teaches environmental science at Indian Hills Community College.
"Last year was the biggest drop ever measured," Houk said, adding that this does not appear to be one of those natural fluctuations sometimes seen in statistics.
She said scientists worry that numbers of monarchs are dropping so fast, one of Iowa's favorites may be heading toward the endangered species list. And even if the species survives, their visits to Iowa may come to a halt.
Annette Wittrock, the naturalist for the Wapello County Conservation Board, has noticed the same thing.
"Their numbers are definitely dropping, and there's concern out there as to whether they'll recover," she said.
Houk said one of the most interesting parts of the monarch life is also contributing to the danger they face: a migration that can be more than 2,000 miles.
They start in the mountain forests of Mexico and fly north, to about Texas. They lay eggs on milkweed — and then die of old age. The generation born in Texas is the group that makes it to Iowa. In Iowa, again, those butterflies lay eggs on milkweed, then we see those brand-new butterflies head toward Canada. And though they haven't figured out how, those Iowa-born butterflies know to leave Canada and head to the same forest their great-grandparents left several generations earlier.
Houk's research has led her and others to believe the danger to monarchs comes from something Iowans consider positive: improved agriculture. As new plant hybrids come on the market, farmers can safely blast their fields with herbicide. And that herbicide is kind to beans, deadly to weeds.