A second wave of migrating Painted Ladies arrived in central Iowa and eastern Nebraska on September 28 when a cool front passed through our area. It had been looking as if the first wave that had arrived on September 5 was about finished, and then all of a sudden there were many more again. These butterflies were generally smaller than those in the first wave, and unlike them, were a mix of different sizes and degrees of wing wear and wing damage. Many of them seem to have ridden the wind toward the west-southwest, reaching the Denver/Boulder, Colorado area on October 3, when the National Weather Service in Boulder spotted radar echoes that they first attributed to migrating birds. They soon realized that the echoes were due to large numbers of Painted Ladies flying northwest with the local winds occurring at that time. Their observation came at the same time that large numbers of Painted Ladies suddenly appeared in Denver for the second time this fall:
From USA Today: Massive Wave of Butterflies Lights Up Denver Weather Radar
From BBC News: Butterfly swarm shows up on Denver radar system
Wind flow patterns from October 1 to today show a persistent low-pressure system in the Denver area with winds spiraling in towards it, sometimes from nearly the entire range of compass directions. From what I’ve seen so far, I think that many of the Denver butterflies sailed from the upper Midwest on west-southwest winds, reaching Colorado in about five days and then dropping downward into the vortex of the low-pressure center.
--Royce Bitzer, October 6, 2017
Painted Ladies are active and abundant in northern Iowa and North and South Dakota. They have been observed there during the weekend either gathering in large numbers or actually migrating. They also seem to be getting ready to migrate here in central Iowa. Their population here has been building up for weeks, with many nectaring on prairie wildflowers. Now that the winds have turned northerly and the air has cooled, there seems to be a new urgency to their activity. This morning, they have been milling about around roosting trees and beginning to head southward. More soon. I'm off to watch them this morning and record their flight directions.
Royce Bitzer, September 5, 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
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
Look out for Red Admirals! Large numbers of these butterflies have been migrating northward across the upper Midwest and southern Ontario, Canada in the last few days in the wake of a strong flow of warm, moist air from the Gulf of Mexico. Some observers have also seen either Painted or American Ladies flying with them. This wave of butterflies has appeared over a wide area of the upper Midwest from northeastern Kansas to Minneapolis, central Iowa, and southwestern Wisconsin within a relatively short time, between April 6 and April 9, suggesting a sudden incursion from elsewhere. To further support this possibility, there has been one report of a steady stream of northbound Red Admirals and Painted Ladies throughout the day on April 8 in Polk County in central Iowa.
-- Royce Bitzer, April 10, 2017
On February 4, 2017, I saw three Red Admirals when visiting Cleopatra's Spring in the Siwa Oasis in northwest Egypt. These were all larger individuals and at least two of them were partly worn and had some wing damage. Had these butterflies been migrants from Europe, or are they part of an overwintering generation that was born here?
--Royce Bitzer, February 13, 2017
During the last several days, the Red Admiral population in central Iowa has rapidly risen as the new summer generation butterflies have emerged. The larger, darker summer butterflies are quickly displacing the smaller spring-generation butterflies from the territories that Red Admirals occupy in the evenings. We have also been seeing some of these fresh individuals flying northward during the day, perhaps migrating, so observers to our north might want to watch for migrants from the south. Also look for the local summer generation butterflies farther north to start emerging during the next few weeks.
Also, be aware that there may be especially large concentrations of Red Admirals emerging within a few miles or kilometers of rivers, lakes, or wetlands where stinging nettles, the larval foodplant, grow abundantly. In late June and early July 2015, huge concentrations of Red Admirals appeared in at least a dozen locations in Iowa; most or all of these sites were near rivers or streams. We will be watching for similar outbreaks this summer. Observers typically report hundreds to thousands of Red Admirals swarming along roadways on either side of a bridge, or when canoeing or kayaking on a river. So, if you see one of these outbreaks, please note the date, location, and its approximate size and report it to us.
--Royce Bitzer, June 10, 2016
We now have a Vanessa Migration Project page on iNaturalist.org for reporting sightings of Red Admirals, Painted Ladies, and other Vanessa species. If you often report observations to iNaturalist, or would like to post photos with your butterfly reports, our iNaturalist project page is another way for you to share your observations with us.
--Royce Bitzer, June 9, 2016
Two Painted Ladies were spotted in Ames, Iowa on March 10, 2016 by two different observers. These sightings occurred nearly two months before the typical first Painted Lady sighting in early May. Another early Vanessa sighting was of a Red Admiral at Point Pelee near Leamington, Ontario on March 16, perhaps a month earlier than is typical for that area. The strong El Niño and unusual weather patterns this winter may be partly responsible for these butterflies' early emergence and arrival. There may be more early arrivals in other places this year, so please watch for them. What you think at first might be an early spring Comma or other anglewing could actually turn out to be a very early Painted Lady - so check carefully!
--Royce Bitzer, March 17, 2016
The strong El Niño event in the Pacific Ocean this winter has given rise to increased rainfall in southern California during the past 30-60 days. Rainfall has also been very heavy this winter farther up the Pacific Coast from central California to northernmost Washington State and perhaps further northward. These conditions are very favorable to give rise to a potentially enormous spring migration of Painted Ladies. Among this massive stream of butterflies may also be West Coast Ladies, Red Admirals, and perhaps even some American Ladies. So please watch for them, share your sightings, and especially note flight directions and estimate numbers of butterflies you see. With the several hundred (or more!) observations we anticipate receiving this spring, we'll have a good opportunity to trace some detailed patterns of butterfly movement as this migration unfolds.
--Royce Bitzer, February 17, 2016