Migration in California--But Are They Monarchs?
Painted ladies are often mistaken for monarchs. They could be monarchs, as it is about the right time of year for them to be inland. But when you read "small" butterflies, "lots" of them, a general northerly movement instead of an easterly movement, and a biology department ID that they are painted ladies, you get the impression that they are really painted ladies and not monarchs. Photographs and vouchers are what are needed to confirm ID's.
This winter we have had heavy rains in the deserts. You have probably seen the reports that there is now a lake in Death Valley. I have a research site near Joshua Tree National Park. Just prior to Valentine's Day, it had 17" of rain (and probably more now). Consider the average for Los Angeles is 15". Add to that the fact that painted ladies food plants number in the dozens and dozens.
the massiveness of the Painted Lady migration extended south half way
by Walt Sakai, Professor of Biology, Santa Monica College, CA