Valley inundated by butterflies

WESLACO — Butterflies are everywhere.

Bryan Zvolanek only has to look outside his office window at Estero Llano Grande State Park to see swarms of fluttering butterflies.

September and October showers produced flowering plants that have led to a butterfly explosion.

“I do remember very vividly on Oct. 14 looking out the window and seeing six or seven yellow-angled sulfurs and ornythion swallowtails,” Zvolanek, the park’s natural resource specialist, said.

Dozens of butterfly species are being spotted throughout the Rio Grande Valley, including a few rarities.

“I would imagine the recent rains are the reason we’re seeing so many that are rare,” Zvolanek said. “To have them day after day in these kinds of numbers is unheard of. I’ve seen people coming from all over the county to see them.”

Some of those rarities include the stunning guava skipper and malachite, a more common resident of northern Mexico. Just as stunning, but more common, are queens, white peacocks, border patches and ceranus blues.
Their numbers, however, pale in comparison to the hordes of American snouts passing through the Valley “as they emigrate out of areas where their food has been consumed or all the females have been mated,” noted entomologist Mike Quinn, president of the Austin butterfly forum.

Spiny hackberry trees, their main source of nourishment, have been full of the snouts.

The number of American snouts passing through is anyone’s guess, but it’s probably not as many as during an 18-day period in 1921.

That year, according to information supplied by Quinn, an estimated 25 million snouts a minute passed over a 250-mile front stretching from San Marcos to the Rio Grande. In 18 days, the estimated number of snouts was 6 billion.

“No telling how many snouts pass through the Valley each year,” Quinn said. “The number moving across South Texas most years must be in the tens (of millions) or hundreds of millions.”

“I know they are known for their population explosions,” Zvolanek said. “You can look up in the trees and still see swarms.”