Butterfly listservs were all aflutter this week with news of butterflies inundating South Texas.  The American Snout butterfly, Libytheana carinenta, arrived en masse in Brownsville and McAllen this week, firing up Facebook, Twitter and email lists with tales of snout butterfly overload.

“American snout butterflies swarm into the Valley,” reported the Brownsville Herald this morning.

“Clouds of those butterflies,” Carina A. Wyant Brunson posted on Facebook from McAllen, Texas.  “It’s hard to walk without bumping into one.”

Dalia R. Salinas of Brownsville relayed that she was sitting outside with her granddaughter “when all of a sudden a swarm of butterflies flew right in front of us. It was amazing, and to see my granddaughter’s face light with amazement was so delightful.”

We had an American snout outbreak in San Antonio in the summer of 2006. The migrating masses clogged car grills, gummed up windshields, and massed on local asters, dogwood, goldenrod and anything else bearing nectar.  There’s a good chance they’re coming our way again soon.

The mottled grey insects disguise themselves as dead leaves when their wings are closed.  In an open-winged pose, they flaunt orange, black and white accents.   They lay their eggs on hackberry trees, a drought-tolerant native considered a trash shrub by some.   But the hackberry is actually a fantastic wildlife plant.  Its leaves provide food for Snout caterpillars and its berries offer important winter sustenance for birds.

The large numbers of migrating Snout butterflies can completely defoliate a hackberry tree, but  “It’s nothing to worry about,” said Michael Nentwich, Forester for the City of San Antonio.   “The trees will recover.  These are seasonal things that happen.”

This year’s weather pattern has lent itself to a butterfly boom, as we’ve written before.   And with temperatures rising earlier in the year, it makes sense the Snouts are arriving in June, rather than August, as they did last time.
In the annals of American Snout butterfly migrations, 1921 ranks as a most remarkable year.

After a world record downpour in Central Texas on September 9-10, 1921, when 36.4 inches of rain fell in an 18-hour period, a Snout butterfly breakout resulted a few weeks later.   “An estimated 25 million per minute southeasterly-bound snout butterflies passed over a 250 mile front from San Marcos to the Rio Grande River,” according to Austin entomologist Mike Quinn’s website Texas Entomology, a trusted and entertaining  source for Texas insect news and info.  Scientists noted at the time that the butterflies’ flight “lasted 18 days and may have involved more that 6 billion butterflies.”