Butterfly Experts Worry About Impact of Texas’ Historic Winter Storm on Monarchs and Milkweed

An expert at San Antonio’s Texas Butterfly Ranch says it’s too soon to tell how last month’s historic winter storm will impact monarch butterfly migration and the growth of their favorite food, milkweed.

Last week, officials with the World Wildlife Fund (WWF) reported the number of this year’s overwintering monarchs in Mexico dropped 26-percent from last year.

All of the migrating monarch butterflies east of the Rocky Mountains pass through Texas during their spring and fall migrations. They only occupied 2.1 hectares of forest at the Mexican overwintering sites — about five acres of butterflies, down from 2.83 hectares or about seven acres reported last year.

Although that decline is attributed to forest degradation at roosting sites, habitat loss and climate change, these unfavorable conditions will be amplified in the wake of the historic freeze.

In 2020, climatic variations in the southern United States were not favorable for the flowering of milkweed and the development of eggs and larvae, WWF said in a Feb. 25 press release.

Texas Butterfly Ranch’s Monika Maeckle said this week that few flowering nectar plants exist at the moment and milkweeds, both native and non-native, appear to have stalled in some areas of the Texas Funnel, the area where monarchs typically lay the first generation of eggs in their multi-generation migration.

She said butterfly gardens along the San Antonio River were frozen to a crisp in February. Tropical milkweed and other species were largely decimated.

Butterflies also appear to be leaving their roosts earlier than usual.

“The monarchs seem to be responding to some other logic, and we can only hope that it’s one informed by a wisdom beyond our perception, and not just more evidence of a climate that’s lethally out of whack with most of Earth’s creatures, which is probably how many Texans are feeling about it these days,” Ellen Sharp, who runs JM’s Butterfly BnB in Macheros, Mexico, told Maeckle in an interview.

Timing matters for the monarch butterfly migration, Maeckle said. The butterflies typically leave Mexico as temperatures climb and days grow longer. Warmer weather makes them burn through their stored fats and pushes them to reproduce.

After breeding, female monarchs start moving north in search of milkweed, the only plant on which they’ll lay their eggs. If there’s no milkweed, they’ll keep flying — or die without reproducing.

“Momma monarchs have to lay most of their eggs in Texas in March and the first week of April for the population to start well,” Chip Taylor, founder of Monarch Watch, told Maeckle.

Lindheimer Master Naturalist Susan Bogle, who works the Butterfly Garden at Tye Preston Memorial Library’s (TPML) butterfly garden said although here are no nectar plants blooming locally at the moment she remains cautiously optimistic about the pending Monarch migration.

“There’s no real food to encourage the monarchs to stop,” she said. “Some milkweed sprouts were spotted in the area the last few days, but they are so small they don’t offer much opportunity as larval hosts,” she said. “But while the roosts in Mexico are restless, they haven’t actually started their migration yet, so hopefully by the time they do come through our area, we’ll have more to support their life cycle. My fingers are crossed. Our own butterfly garden just had its spring cleanup, so all the plants have been pruned fairly severely. There’s not much there to attract a monarch. But just give it some warm weather and some rain — that’ll make a real difference.”

Editor’s Note: This article is condensed from a post by Monika Maeckle with TexasButterflyRanch.com. Physically, the Texas Butterfly Rranch encompasses the geographic area around Austin, San Antonio and the Texas Hill Country, the famous ‘Texas Funnel’ through which all monarch butterflies east of the Rocky Mountains pass during their fall migration. Maeckle cultivates a pollinator garden in downtown San Antonio. For more information, visit TexasButterflyRanch.com.