A lacy, cloud-like pattern drifting across a Denver-area radar screen turned out to be a 70-mile-wide (110-kilometer) wave of butterflies, forecasters say.

Paul Schlatter of the National Weather Service 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 southbound in October.

He asked birdwatchers on social media what it might be, and by Wednesday 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, not their own colors.


Painted lady butterflies
Midwestern radar stations occasionally pick up butterflies, but Schlatter believes it's a first for Denver.

An unusually large number of painted ladies, which are sometimes mistaken for monarch butterflies, has descended on Colorado's Front Range in recent weeks, feeding on flowers and sometimes flying together in what seem like clouds.

Sarah Garrett, a lepidopterist at the Butterfly Pavilion in Westminster, Colorado, 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, but 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.

Source: Associated Press

I remember years ago the Monarch's migration came through N. Texas.
The flew just over the tree tops and lasted about a week. Sure was
something to see. I didn't know there was a Painted Lady migration too.

I think that the Monarchs are conservative and Painted Ladies are liberal

Punch up what Starlings do in Italy. Its great to look at the videos, but they really are a problem.

I lived in an area that had problems with crows. Known all over the state and we had to listen to them all the time. They never bothered me at all.

They was an alarm clock in the morning to me. Tons of them all over in every tree you can imagine in the morning.

Starlings are nasty birds. They are not native to n. America, some
idiot brought them over from England to control insects.

Amazingly beautiful colours.

Oh, silly me, I thought it was because of their political affiliation.

I remember seeing them as a kid in Dallas, I never knew they were migratory...

Who Liberals? Yea, they go which ever way the wind blows.

we use to get big flocks of the monarchs. but i haven't seen that in years

WOW! What I wanna know is the count.

That's pretty cool! Have seen a lot of the same kind of butterfly in the area I'm at recently. Hadn't seen them much in previous years.

Seen this the other day just totally awesome would love to be where I could see them flying....

Hope they got out of Colorado before the snow hit..