Originally posted by TER-OR
Great shot!
I'm not sure how much of the US populations migrate, but they do seem to do so in numbers. The European population seems better studied. It's really fascinating to think these little insects travel so far.
Now we need to get people to stop planting butterfly bush and plant verbena etc. instead!
I read that a big reason for their population surge in southern California this year was due to all the spring rain they had in the desert areas. Lots of flowers blooming.
As of 2009 only Oregon Department of Agriculture approved seedless butterfly bushes can be propagated, transported, or sold in Oregon according to their noxious weed quarentine.