Cache Valley is witnessing a mass butterfly migration on a scale not known for nearly two decades — and another two decades before that.
Small orange-and-black butterflies identified as painted ladies have been drifting through the valley by the thousands over the past several days, prompting local residents to speculate about what’s going on.
But it’s not just a Cache Valley or Utah thing. Salt Lake City butterfly researcher Todd Stout says the epic migration is occurring throughout the West.
“The painted lady butterfly actually comes north every year. Some years I’ve hardly seen any, but this year they’ve exploded,” Stout said, comparing the numbers to notable mass influxes of the same species (Vanessa cardui) in 1991 and 1972.
Reports of the unusual natural event first started surfacing in California in February, and some biologists there equated the large butterfly numbers with the wildflower “superbloom” occurring in the Mojave Desert early this year.
“Actually the root cause is precipitation, which creates a superbloom,” Stout said. “It’s all that water.”
Stout, a former president of the Utah Lepidopterists Society who hosts a website and blog devoted to butterflies, urged local parents and teachers to use the migration as a learning opportunity.
“This is an unprecedented year for educators and school teachers to discuss the painted lady butterfly and their migratory story during their insect units,” he wrote on his blog. “It is not difficult to find painted lady eggs and caterpillars between now roughly through the end of May anywhere in the state where weeds grow.”
Stout’s blog went on to explain that dandelions and weeds, as opposed to flowers, are the most common stopping places for painted ladies as they pass through the region. “Ironically, you may see fewer painted ladies if you have an immaculate garden, free of weeds,” he said.
Noted Cache Valley butterfly enthusiast Ron Hellstern took his grandchildren out last weekend to observe clusters of painted ladies collecting on the dandelions near his home in Nibley. Hellstern noted painted ladies should not be confused with the larger, more brightly colored monarch butterflies that he has spent years working to save from extinction through tagging, milkweed-planting campaigns and other means.
Each year, the appearance of painted ladies in Cache Valley is a precursor to monarch arrivals.
“Monarchs aren’t quite here yet. There are reports of them in Southern Utah, and they’re heading this way,” said Hellstern, who is watching with “fingers crossed” to see if the species shows signs of bouncing back from frighteningly low numbers in the past year.
For his part, Todd Stout is not as concerned as Hellstern and other biologists about the fate of monarch butterflies, largely because periodic population surges like this year’s painted lady event and the unexpected re-emergence of endangered swallowtail butterflies in Utah’s West Desert in recent years.
“I have no doubts that butterflies like monarchs will be OK,” Stout said. “Trust me, butterflies are more powerful than people realize.”