Sandy Liebhold here is another one with a bit more data. The wild thing is even if the overwintering colony does poorly, these females can lay 200 eggs and have 4 generations a year, so a single pair can produce 100 million before the next overwinter year. The graphic in this is skewed to showing recent declining years, but populations have were low in the 80s and increased rapidly to the peak the mid 90s. The recovery was likely due to the strong potential of having 4 generations a year. So that hints that something is happening once they get north and not allowing for this recovery to happen. A lot that is not known about this species.
Posted on: Thu, 30 Jan 2014 13:29:00 +0000