Little Butterflies Are All Over Central Texas. Here's Why.

Oct 2, 2020

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The last couple weeks you might have noticed a large number of small butterflies drifting through Central Texas. The view from a park or garden can be magical, as hundreds meander through the air flashing specks of brown, black and yellow. The view from a highway is less so, as the bugs reel between vehicles before getting squished by an oncoming windshield. 

No matter how you’ve experienced them, you’ve probably wondered, “What are these things?”

They’re snout butterflies. And this year has been a good one for them in Central Texas.

It all comes down to weather. August was hot and dry, and September was cool and wet.

Mike Quinn, an Austin-based invertebrate biologist, said drought in August is “shown to knock out all the predators and parasitoid insects that keep the snout butterfly population in check.” A wet September gives the snout caterpillars plenty of fresh hackberry leaves to munch on.  

“Because of the reduction in the predators, a high percentage of the snout butterfly caterpillars survive to adulthood,” Quinn said. “And so you have what we're experiencing right now.”

What we're seeing are "mass movements," not migrations, he said. Unlike monarch butterflies, the snouts are not traveling a fixed seasonal path between two set points. They are instead seeking out food and mates wherever they may be.

“They're moving out of an area of exhausted resources,” Quinn said, “so the movement can be multi-directional.”

While Quinn says the number of snout butterflies in Central Texas this year has been “wonderful to see,” it doesn’t hold a candle to some massive emergences in the past.

“There’s records of them being so abundant that they cause streetlights to come on during the day,” he said. “So, we're not seeing anything like that right now.”

Got a tip? Email Mose Buchele at mbuchele@kut.org. Follow him on Twitter @mosebuchele

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