During a recent drive along U.S. 90 from Uvalde to Marathon, we saw multitudes of tiny snout butterflies fluttering over the road like party confetti -- and splattering against the windshield.

At every roadside gas station along the highway, smashed butterflies were an unsightly mess on the windshields of other cars. A woman at one stop looked at me and muttered, "Nasty little things," as she wielded a wet squeegee across her windshield.

Our car looked like a snout graveyard.

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But birds look at the dead butterflies as bountiful food. House sparrows will eagerly pluck dead snouts from the car's windshield.

You'd think most snout butterflies would have been killed off by highway traffic. Not so. Hordes of these tiny snouts swarm around every convenience store and gas station, alighting on bushes and ornamental trees.

American snouts are drab brown butterflies about an inch and a half long. When perched with folded wings, they look like dead leaves. But their open wings reveal a burnt orange patch accented with white dots. A long appendage, called a labial palpi, extends from their heads to form a wiry-looking snout.

They're common across North America, from southern New York to the desert southwest, but they usually go unnoticed, until huge numbers suddenly and unpredictably emerge. We saw a massive flight of snouts in 2006 along U.S. 90 past Uvalde.

Mike Quinn, curatorial associate to the UT Insect Collection, once told us that swarms of snouts occur about once a decade. "Scientists have found that such outbreaks of snouts follow widespread rain preceded by a significant period of drought," Quinn said.

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During dry periods, fewer predatory insects, such as wasps and praying mantises, are around to feed on butterfly caterpillars. But during uncommon rainy periods in arid parts of the state, hackberry trees flourish. The hackberry leaves nourish snout larvae, which later may result in hordes of snout butterflies.

At least 3 inches of rain fell on Uvalde during July, while Big Bend National Park experienced almost 2 inches. Those rains probably explain the recent snout hordes crisscrossing U.S. 90 and getting splattered against car windshields. But it was a temporary event. Like all butterflies, American snouts short-lived, surviving anywhere from a few days to a little over a week.

* American snouts are common in Texas from spring to autumn.

* Hackberry trees, with several varieties throughout the state, are the host plant for snout larvae.

* Snouts are members of the Nymphalidae family of butterflies that include Texan crescents and monarch butterflies.

* The lifecycle of a snout from an egg to a caterpillar and then to an adult butterfly occurs during approximately 12 days. But female snout butterflies can lay 200 eggs during their two weeks of life.

* Dead snouts smashed against vehicles cause no harm to windshields or car paint and can be washed away with a watery dishwashing liquid like Dawn.

Email Gary Clark at [email protected]. He is the author of "Book of Texas Birds," with photography by Kathy Adams Clark (Texas A&M University Press).