Thousands of unexpected visitors—butterflies!

Butterflies are often viewed as powerful symbols of change, hope and life. As the rains subsided for a moment or two last week, many Claremont residents enjoyed not only a fluttering creature in their home garden, but thousands of butterflies migrating west.

“We’re seeing an unusual number of painted ladies,” said Paul Faulstich, professor of environmental analysis at Pitzer College.

The painted lady, according to Mr. Faulstich, is referred to as an “irruptive migrant,” meaning its travel isn’t affected by seasons or geographic patterns.

Nancy Hamlett, retired professor of biology at Harvey Mudd College, has been documenting the species list at the Bernard Field Station, among other projects, since 2001. She also coordinates the butterfly monitoring program for a group called PRISSM—The Partnership of Regional Institutions for Sage Scrub Monitoring.

According to Ms. Hamlett, painted ladies (Vanessa cardui) are currently migrating through our area. On Monday, February 25, Ms. Hamlett photographed and documented the butterflies as they were nectaring on common fiddleneck (Amsinckia intermedia).

“Painted ladies do normally migrate,” Ms. Hamlett said, “but the number this year is quite unusual in my experience.”

But as Jean Collinsworth posed in a recent Haiku, where are they going?

“In general, the painted ladies are migrating from northern Mexico all over the US and into Canada,” Ms. Hamlett explained. “I would guess the ones we see here are heading to Central then Northern California, Oregon, Washington, and Canada.”

According to Butterflies and Moths of North America, “Occasionally, population explosions in Mexico will cause massive northward migrations.”

The rainy weather, though sometimes oppressive, is providing more to area residents than just the occasional bout of SAD—seasonal affective disorder.

“Evidence suggests that their migrations may be linked to the El Niño climate pattern. The increased presence of painted lady butterflies, along with other butterfly species, is being triggered by a wet winter that has fueled vegetation growth, giving caterpillars plenty of plants to eat,” he said.

And, he says, the low-flying painted ladies are often easier to spot when migrating, because on average they hover between six to 12 feet above the ground. 

But as Mr. Faulstich notes, “This all provides for happy viewing!”

—Kathryn Dunn


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