Invasion of the Painted Ladies

Painted Lady butterflies (Vanessa cardui) are resident in the deserts of northern Mexico, so why are they showing up in Deering in large numbers this fall?  In most years, they are uncommon or absent in our area.  For reasons not fully understood, Painted Ladies occasionally migrate northward in huge numbers, and under favorable conditions their numbers increase as they migrate northward with each successive generation.  Then in the fall they migrate southward to escape the cold temperatures.  We may be witnessing one of the greatest migrations of Painted Ladies to occur in our area in a lifetime.  This past weekend, over a dozen were observed nectaring on zinnias in our flower garden.  This phenomena isn’t just happening in Deering, but is being reported throughout New England and elsewhere across the continent.  If fact, this year the migration has been large enough to register on the National Weather Service’s radar imagery.  I hope you enjoy the flash of orange and black wings in your gardens as we have.