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<h1><b>In Texas, Conditions Lead to a Rabble of Butterflies
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Bryce Harper for The New York Times<br><br>
Parts of South Texas are under siege by swarms of butterflies, many of
which do not manage to live out their full two-week life spans. <br><br>
By
<a href="http://topics.nytimes.com/top/reference/timestopics/people/b/ralph_blumenthal/index.html?inline=nyt-per">
RALPH BLUMENTHAL</a><br>
Published: July 27, 2006<br><br>
GOLIAD, Tex., July 25 For a moment, Carol Cullar thought she was seeing
fall leaves gusting down the highway south of Quemado, Tex., on the
Mexican border.<br>
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Bryce Harper for The New York Times<br><br>
Mike Quinn, an entomologist with the State Parks and Wildlife Department,
tracking butterfly migration. <br>
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But it is blistering midsummer, Ms. Cullar, director of the Rio Bravo
Nature Center in Eagle Pass, realized. And leaves would not all be flying
north at two or three feet off the ground car radiator height.<br><br>
These were butterflies. At least 200,000 of them, she guessed, perhaps a
half-million. It was an invasion, she said, “like nothing I’ve ever
seen.”<br><br>
South Texas is under siege from swarms of airborne migrants: tens of
millions of Libytheana bachmanii larvata snout butterflies to y’all
along with Kricogonia lysides, or yellow sulfurs, that have taken
advantage of an unusual drought-and-deluge cycle to breed in spectacular
if not record profusion.<br><br>
The smallish, dull-colored snouts take their name from an appendage they
attach to branches to disguise themselves as leaves.<br><br>
Blinded drivers who have to pick the critters off their grilles to avoid
dangerous engine overheating are less than enthralled, as are the
mottephobes, who fear butterflies and moths. But lepidopterists are
thrilled with the spectacle, which they predict may be only the beginning
of a population explosion of snouts. <br><br>
They concede, however, that it could denude considerable swaths of
<a href="http://topics.nytimes.com/top/news/national/usstatesterritoriesandpossessions/texas/index.html?inline=nyt-geo">
Texas</a> hackberry trees and other choice caterpillar habitats, at least
for a while.<br><br>
“Snouts, I’m at a loss for words,” wrote Joshua S. Rose, a biologist and
dragonfly specialist with the World Birding Center at Bentsen-Rio Grande
Valley State Park near Mission, Tex., in an e-mail message to friends
Tuesday. <br><br>
“They’re beyond any mere collection of individual animals,” Dr. Rose
wrote. “Like a flock, herd, swarm or even horde, they have more in common
with a geologic or climatic force, the Gulf Stream or an Arctic front.
While driving, we can’t dodge butterflies, we can only aim the car at the
parts of the road where the density is lowest.”<br><br>
Lawrence E. Gilbert, professor of integrative biology and director of the
Brackenridge Field Laboratory at the
<a href="http://topics.nytimes.com/top/reference/timestopics/organizations/u/university_of_texas/index.html?inline=nyt-org">
University of Texas</a>, said such mass emergences were hardly known
outside the Southwest, although they also occurred with another butterfly
species in Africa. Dr. Gilbert filled a bucket last week with hundreds of
dead snouts and sulfurs collected from a roadside near Alice, many of
which never made it to the end of their two-week life span.<br><br>
The phenomenon sent Mike Quinn, an entomologist with the State Parks and
Wildlife Department, beelining here on Tuesday from his Austin office to
track the butterfly migration. <br><br>
Cellphone pressed to his ear, Mr. Quinn, 43, polled area rangers for
promising sightings. He had high hopes along the reservoir at Choke
Canyon State Park. “We were told this was snout central,” he said. But
they had since fluttered by. <br><br>
“Tons? Right as we speak, or the last few days?” Mr. Quinn asked another
tipster. “Let me get a specific from you. Exactly where is
everywhere?”<br><br>
One parks employee, Linda Lopez, tried to be helpful. “The snout ones are
the little brown ones with variegated color?” she asked.<br><br>
“You got it,” Mr. Quinn said. “We’re looking for the river of
butterflies, not just the stream.” <br><br>
Driving a circle of perhaps 200 miles from Goliad around Choke Canyon and
back, Mr. Quinn never did find a real swarm, although he was tantalized
by evidence of their ubiquitous presence on the radiators of
tractor-trailers. <br><br>
But he stamped through the brush along the water, flushing clouds of
snouts, sulphurs and little blues, which all fluttered excitedly around
him. He also saw considerable evidence of the stripped trees that had
nurtured the caterpillars, and specks of caterpillar droppings called
frass that fertilize the vegetation and help it recover from the feeding
frenzy. <br><br>
Mr. Quinn and Dr. Gilbert said the butterfly proliferation had been set
off by drought conditions that decimated the caterpillar’s natural
predators, followed by drenching rains that prompted hackberry trees to
put out green shoots, quickly attracting the egg-laying caterpillars that
could briefly thrive without enemies. <br><br>
“It was a double pop,” Dr. Gilbert said, two cycles in succession that
reinforced the effect over the 12-day passage of egg to adult.<br><br>
With insects generally suffering a 99 percent mortality rate, said Mr.
Quinn that is, only 1 egg of 100 laid making it to maturity a sudden
improvement in the odds can radically disrupt the usually exquisite
balance of nature.<br><br>
Where, how and why the swarms migrate is less clear. Butterflies are not
social creatures flying in flocks like birds but are drawn to flowers as
sources of nectar and pollen. <br><br>
Dr. Gilbert said that in studying migrating snouts he was struck to find
that up to 95 percent were males. “The older males get most of the
matings as the hatch continues,” he theorized. “Then the new guys don’t
have a shot because of the old guys, and they just say, The hell with
this, and they go.”<br>
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