Summer Generation Red Admiral Outbreak in Iowa

June 21, 2017

If you live in Iowa, have you been seeing the abundant Red Admirals that have emerged or arrived within the past 10 days? Following a rain in the Ames area on June 13, Red Admirals were suddenly all over the place the next day. I went outside on the Iowa State University campus on the afternoon of June 14 and saw dozens of fresh new ones nectaring in a linden tree. Many more are present now than there were before this outbreak occurred.

Another place I saw many fresh ones was at Orange City on the morning of June 15. These seemed to be localized within a limited area of northwest Iowa, because I saw only one butterfly near Sutherland and none near Newell on the same day. The Orange City butterflies, however, didn’t seem to have been induced to emerge by recent rainfall, since that part of the state missed out on the rain that reached most of Iowa on the 13th.

I also received a report of 200 nectaring in a linden tree near Marshalltown, also on June 15. There was also a "huge" Red Admiral hatch near the Iowa Arboretum, just west of Luther, during the same week. Their numbers were "incredible!"

Who else has been seeing them, and where? These large numbers seem to be occurring in some parts of Iowa and not others. For example, on June 16, I was in the Mason City and Eagle Grove areas (north-central) and didn’t see any near Mason City, and only two near Eagle Grove, even though the weather conditions were as favorable then as they had been in northwest Iowa the day before.

-- Royce Bitzer, June 21, 2017