Ecologists know the Monarch butterfly migration is changing. But Dara Satterfield’s research out of the University of Georgia suggests butterflies that stay in the U.S. for the winter pass on more disease and parasites to their offspring. Preserving the full migration to Mexico is important for the health of the overall Monarch population.
“If they’re trying to travel to Mexico with this protozoan parasite, many of them don’t make the journey. And that’s a good thing for the population at large. You end up with a healthier population of Monarchs,” said Satterfield, the lead author of the UGA study.
Satterfield’s research found there could be a simple reason the butterflies are sticking around.
It’s tropical milkweed, and it’s what most butterfly enthusiasts plant in Texas.
“It’s beautiful, it’s easy to grow, the Monarchs love it. But there’s this problem that it doesn’t die back in the winter and provides food for the Monarchs all year,” Satterfield said.
So while tropical milkweed does a good job of feeding Monarchs, it does too well at keeping them in town for the winter.
At Buchanan’s Native Plants in the Heights, Diane Bulanowski is the de factor butterfly expert. She sports glasses vaguely shaped like butterfly wings. Bulanowski said it’s not wrong to plant tropical milkweed. It’s just that a lot of people are growing the plant at the wrong time of year.
“People that are butterfly gardening should cut their milkweed back, mid-October. And that will help the butterflies begin their migration and not stick around,” said Bulanowski, Buchanan’s Plant Purchaser.
Bulanowski said Houstonians should also consider growing native milkweed varieties that die back in the winter. It seems the word is spreading: Buchanan’s has trouble keeping native milkweed seeds in stock.
Satterfield and Bulanowski suggest planting native varieties like Antelope Horns milkweed, Green milkweed and Showy Milkweed.