A University of Kansas ornithology collection manager was looking for birds before dawn at the Kansas University Fitch Natural History Reservation north of Lawrence when he spotted tens of thousands of caterpillars munching on hackberries.
There were so many of the insects that what Mark Robbins thought was a soft, gentle rain falling in the darkness actually was the sound of thousands of caterpillars defecating. “I have never seen anything like this,” he said.
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Robbins noticed barren branches of hackberry trees as the sun came up where the caterpillars had fed as they get ready for their transformation into Hackberry Emperor butterflies.
In his nearly two decades of walking through the woodlands, Robbins said he has never seen so many of the caterpillars so early. “It's very extraordinary,” he said.
Robbins is predicting a “quiet bedlam” when the caterpillars become butterflies. Dave Rintoul, associate director of Kansas State University's biology division, knows firsthand what that could be like.
More than a decade ago, Rintoul ran into what he described as a tornado of butterflies at a Fort Riley bird-banding station along the Kansas River. The area was heavily covered in hackberries, a common Kansas woodlands tree.
“It felt like there were more butterflies than air. And that is what it is going to be like,” Rintoul said. “In a couple of weeks, that is going to be quite a scene.”
It's unclear why the massive population has shown up this spring, but Robbins suspects the unusual warm winter led to more caterpillars surviving.
Robbins walked into the heart of the caterpillar infestation at the Fitch Natural History Reservation late last week, and that time the sound of droppings was more like a shower than a gentle rain. Every few seconds a caterpillar plummeted to the ground like a shooting star.
Throughout the woods are patches of leafless hackberry trees, looking like hot spots of barren vegetation left behind after a forest fire. Robbins thinks the lack of leaves will lead to more undergrowth on the forest floor this summer.
The caterpillars are a good thing for birds, he said, which will be able to feast on the fattened bugs.
“Literally they are just sitting in the trees stuffing themselves,” Robbins said.
Information from: Lawrence Journal-World