Red Admirals have been migrating northward through Iowa in larger numbers beginning on Sunday, May 3. Some Red Admirals have been here for the past few weeks, but the larger numbers we’re seeing since this weekend appeared rather suddenly here in central Iowa on May 3, migrating northward, and they still continue to do so. They arrived in Story County, Pocahontas County, and doubtless in many other parts of the state at this time, flying toward the north-northeast. They probably came with the arrival of the first warm, humid air mass to reach our area this spring. When the winds picked up from the south, so did the butterflies, riding the wind flow northward from some as-yet-unknown area to the south.
Accompanying this wave of Red Admirals has been a relatively small number of American Ladies traveling northward with them.
From where have these butterflies been coming? Have any observers in states south of Iowa been seeing this migration before May 3?
-- Royce Bitzer, May 6, 2015