Wave of butterflies lights up weather radar
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A lacy, cloud-like pattern drifted across a Denver-area radar screen. It turned out to be a 70-mile-wide (110-kilometer) wave of butterflies. That's according to forecasters.
Paul Schlatter works for the National Weather Service. He said he first thought flocks of birds were making the pattern he saw on the radar Tuesday. But the cloud was headed northwest with the wind and migrating birds would be headed southbound in October.
He asked birdwatchers on social media what it might be and by Wednesday he had his answer. People reported seeing a loosely spaced net of painted lady butterflies drifting with the wind across the area.
Schlatter said the colors on the radar image are a result of the butterflies' shape and direction. The colors he saw were not their own colors.
Midwestern radar stations occasionally pick up butterflies. But Schlatter believes it's a first for Denver.
An unusually large number of painted ladies are sometimes mistaken for monarch butterflies. They have descended on Colorado's Front Range in recent weeks. They feed on flowers, sometimes flying together in what seem like clouds.
Sarah Garrett is a lepidopterist at the Butterfly Pavilion in Westminster, Colorado. She said people from as far away as the Dakotas have called to report seeing the butterflies, whose population typically surges with plentiful flowers.
Research on the painted ladies in North America is limited. Scientists believe they migrate to the southwestern United States and northwestern Mexico in the fall. In Europe, studies using radio tracking have shown they migrate south from Europe to Africa in the fall and return in the spring. Studies also show that monarch butterflies often use wind to their advantage and glide on currents for periods of time, Garrett said.