Tehachapi News

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A huge wave of travelers passed through Tehachapi last Monday and Tuesday on their way north. There were tens of thousands of them but they had no effect on local traffic because they weren't using the roads, they were flying — it was an exodus of Painted Lady butterflies on their annual migration to recolonize North America.

These orange and black butterflies with white highlights generally pass through this area every year in late March and early April. Observant Tehachapi residents might have noticed that all the butterflies were moving from south to north. Occasionally they alter their course to avoid buildings or natural obstacles, but the Painted Ladies are all headed north.

Though the Painted Lady butterfly (Vanessa cardui) can be found in every state and well into Canada in late spring and summer, hard frosts in the fall and winter kill off any remaining butterflies, with the possible exception of a few that may survive in coastal California and extreme southern Arizona.

Enough adults survive in Mexico to lay abundant eggs, which hatch into caterpillars in January and February in the far Southwest. These caterpillars, which are mostly brown or black with some yellow highlights and short white spines, feed on thistles and other host plants, grow quickly and then form a chrysalis and emerge about 10 days later.

Upon completing their metamorphosis from caterpillars into attractive butterflies, Painted Ladies begin to stream north into the United States. The timing of their flight and the number of butterflies varies from year to year and is influenced by winter temperatures and rainfall. In favorable years, the population of Painted Ladies is hard to fathom as many millions of these nectar-loving flyers stream north to repopulate the United States and Canada.

Unlike the yearly migrations of Monarch (Danaus plexipus) butterflies, the Painted Lady migrations are a one-way trip without a corresponding return in the fall.
Painted Ladies don't fly high above the ground in the region of relative safety used by migrating birds — instead they usually flutter and sail a few feet above the ground, exposing them to many hazards including cars, whose windshields, radiators and grills often bear the remains of Painted Ladies that didn't survive an encounter with speeding auto or truck.

Sheer numbers enable the species to withstand such carnage and other creatures make use of the bounty of butterflies. Last week I watched two different ravens make repeated forays onto Highway 202 and Cherry Lane to retrieve and eat butterflies that had perished in collisions with cars. Painted Ladies don't feed on milkweed plants and so lack the bitter taste imparted to Monarchs, which are unpalatable and thus largely protected from predation.

Like most butterflies, Painted Ladies are bright and noticeable when viewed from above with their wings opened flat, but they are well camouflaged by their cryptically-colored underwings. The upperside and underside of their wings appear so different they don't even look as though they belong to the same butterfly.

Not all the Painted Ladies pass through Tehachapi and keep going — a few can be found in gardens and meadows in this area throughout the spring and summer. As widespread as they are (Painted Ladies are frequently called “the most cosmopolitan butterfly in the world”) they don't congregate and aren't found in large numbers except during their spring migration. Apparently they disperse and spread out as they reestablish themselves in the United States.

Keep your eyes open for the sight of Painted Lady and other butterflies now that the weather has warmed up. Butterflies are one of the pleasures of spring in Tehachapi, a reward for making it through another cold and windy winter.
Have a good week.