Painted Ladies have been on the move this spring. Their first generation this year may have gotten started in southern California during the enormous February-April bloom of desert annuals that provided abundant food plants for their caterpillars. Although there didn't seem to be a widespread Painted Lady outbreak across California - instead I received reports of small numbers there for the most part - there have been scattered reports of large outbreaks in the western U.S. and Canada between early April and now. These include:
Nevada southwest and west of Las Vegas: April 3 - 5, 2017. On April 3 and 4, Painted Ladies were flying from east to west at rates of 5 per minute or more for periods of 4 and 6 hours respectively. Activity had greatly decreased on April 5, with only about 10 spotted during a half-hour period around 10 a.m.
Medford, Oregon: May 2, 2017. An observer completed a point count of Painted Ladies at 2:30 p.m., observing 168 butterflies per hour flying generally east-southeast to west-northwest (the starting time wasn't mentioned).
Albuquerque, New Mexico: Mid- to late May 2017. Painted Ladies were present in large numbers here since perhaps the middle of May. Hundreds were seen nectaring on a linden tree on May 26.
Alberta, Canada, between Red Deer and Edmonton (south to north) and Alder Flats and Innisfree (west to east): Painted Ladies have been abundant in this area since about June 5, and continued to be as of June 17.
Northwest Iowa, Orange City and near Calumet: June 15. Fresh Painted Ladies were locally abundant in Orange City and also at Iowa State University's Northwestern Research Farm south of Calumet. About 20 were seen within a half hour at each location. Another observation suggested that this abundant population was somewhat localized on June 15. Two other sites near Newell, in west central Iowa about 60 km southeast of Calumet, had only a few or none on the same date. Nor were Painted Ladies present farther east in the Mason City, Eagle Grove, or Ames areas on June 16, although weather conditions were likewise favorable.
If you see Painted Ladies in your area, including larger numbers such as described in the above reports, please report them here or on our iNaturalist project page, https://www.inaturalist.org/projects/vanessa-migration-project.
-- Royce Bitzer, June 19, 2017