Red Admirals continue to become more abundant in the upper Midwest and southern Ontario, despite several intervening interludes of cold weather. They migrated in on days when warmer, moister air was flowing up from the south. The first of two migration waves occurred on April 15-16, resulting in an abrupt increase in both butterflies and observers noticing them for the first time this year. Locally, I observed Red Admirals flying consistently northward on the 16th, as well as a threefold increase of Red Admirals in territories late that afternoon, as compared with a previous survey a week earlier. After a cooler period, a second and perhaps larger wave arrived in various parts of the Midwest from April 21 -24, again resulting in a further increase in the local population. Observers in Minneapolis, southern Wisconsin, southern Michigan, and southern Ontario reported large increases in Red Admirals, and some substantial northward migrations occurred in southern Ontario, raising the question of whether Red Admirals were actually crossing Lakes Erie and Ontario.
A subsequent period of cooler weather has quieted their activity recently, with far fewer seen during a local survey on April 29th than during a previous one on April 23. Whether this is due to the butterflies sheltering from the cool weather or to an actual decrease in numbers remains to be seen.
-- Royce Bitzer, April 30, 2019
There was an extensive northward migration of Painted Ladies in southern Oregon from at least between April 21 to April 25, 2019. Three different observers recorded migration rates ranging from between 68 northward in 2 hours on April 23 to 300 northwestward in 15 minutes on April 25. These butterflies are likely part of a second generation that originated farther south somewhere in California. From other reports I've received, conditions in California and southern Nevada have been so favorable that two generations of Painted Ladies grew and thrived there on an abundance of nectar and larval food plants.
-- Royce Bitzer, April 30, 2019
As I was writing here last month, I’ve been following the enormous Painted Lady migration that’s been happening in California and the Southwest since late January to early February. While this migration continues northward, it’s now also time to turn more attention eastward as wind and weather patterns have become favorable for Red Admirals and American Ladies to migrate northward into the upper Midwest, the eastern states, and southern Ontario. Painted Ladies may be arriving in our area somewhat later this spring, perhaps from the west, or perhaps from a smaller population that overwintered in Texas.
Red Admirals have arrived in the upper Midwest, and are already here in Iowa – they seem to have come with the warm southerly wind last Saturday, April 6, resulting in sightings in central Iowa's Story and Boone Counties on that day. They were also spotted in Omaha, Nebraska on April 2, and in Kansas City, Missouri on April 5. Chip Taylor, the director of Monarch Watch, spotted his first two in Lawrence, Kansas on April 6th, while suggesting that Red Admirals could have arrived there a few days earlier. A first-of-the-season Red Admiral was also seen on April 8 in Kingsville, Ontario, near Point Pelee National Park.
Since yesterday, it's likely that any further northward Red Admiral movement will be literally stopped cold (at least temporarily) by an enormous low-pressure system passing through the northern Great Plains, Minnesota, and Wisconsin. This storm has brought us two days of high winds in central Iowa, and heavy snow in states to our north. To our south, temperatures were in the 60s F in southern Iowa and in the low 80s in Kansas. Under these conditions, any additional Red Admirals arriving from farther south might stop migrating and accumulate in these areas, resulting in a sudden increase in the number present.
-- Royce Bitzer, April 11, 2019
Painted and West Coast Ladies are not the only butterflies in the western United States to be undergoing an outbreak. California Tortoiseshells have also been present to abundant in some places in northern California and Oregon where Painted Ladies probably have not yet arrived in any large numbers. They look like this: https://bugguide.net/node/view/1447798. While they are interesting butterflies in their own right, and worthy of further study, they are not Painted Ladies, so please be careful not to confuse the two when reporting Painted Lady sightings. Also, according to a March 18 posting on DesertLeps, California Tortoiseshells have also become abundant in the area of southern California around the Santa Rosa and San Jacinto Mountains National Monument, replacing the Painted Ladies, which are surprisingly not that common there now and seem to have mostly departed the area. However, Painted Ladies were still abundant in southern California on March 16 near the Mescal Range in San Bernardino County, CA, about 138 miles (222 km) to the north-northeast; no California Tortoiseshells were observed there.
-- Royce Bitzer, March 19, 2019
The ongoing Painted Lady migration is well underway, after a seeming delay in some areas due to cool weather. Large numbers were passing through Palm Springs, California on and before March 2, 2019, and some of these butterflies were observed flying westward. They also became abundant in the Las Vegas area around March 4, and continue to be present there in large numbers. Most recently, an enormous swarm has been flying northward through the Los Angeles area, both yesterday and today, March 12. Painted Ladies are now widespread throughout southern California, including in Borrego Springs, where an extensive northward migration was underway on March 11. In Yuma, in the southwestern corner of Arizona, Painted Ladies have likewise been flying in huge numbers for the last two to three weeks, mainly in a northwestern direction. The entire outbreak was likely triggered by considerable local rain associated with the current El Niño event, followed by prolific blooms of desert annuals and growth of larval food plants.
Although the butterflies have often been reported as flying generally northward, there seems to be substantial local variation in flight direction in much the same way as occurred during a similar large and well-observed migration from February through April 2005, as you can see by looking at our flight direction map for that interval. Once there, check the Painted Lady box, enter that range of dates, and zoom in to see the directions of the arrows and get an impression of how the migration proceeded and spread during spring 2005.
-- Royce Bitzer, March 12, 2019
Painted Ladies have been appearing in the desert Southwest since early February, and large numbers of migrants have been spotted in several locations in southern California and northwestern Mexico since February 15. What will happen next? Will this be a typical outbreak of the kind we see every few years? Or is this just the start of another phenomenal Painted Lady explosion to match the continent-wide migration of 2017?
Although conditions seem favorable for this generation to multiply and migrate, what seems to precipitate the rare extensive and enormous migration waves is for the next several spring and summer generations in their turn to encounter optimal conditions to thrive and breed - timely rainfall, abundant nectar plants, abundant larval food plants - wherever they might go. If that happens - and it's by no means certain at this point - we could be looking at another peak year for Painted Ladies. We'll just have to wait and see. In the meantime, please keep watching for them and reporting your sightings!
-- Royce Bitzer, February 18, 2019
The Red Admiral and Painted Lady Research Site will have a new format, perhaps as soon as tomorrow. Revisions have been underway for the past several months, and we have been reviewing and editing the changes during the past three weeks.
Among the changes will be a new interactive Google map with more options for viewing observations by a specific range of dates (rather than simply by a range of months as in the map we've had), as well as for viewing all the observations for a particular month or set of months over two or more years. These changes allow the map to show more specific periods of time during migrations, as well as multi-year seasonal ranges of each species of butterfly. The new map also offers both roadmap and satellite views, to make both viewing existing points and adding new observations easier, and map points of any color will also show up much more clearly against the new backgrounds. Clicking any point on the map will now show its geographic coordinates as well as all of the information shown previously. We have also revised the page for entering new observations. Besides searching for a location by name or clicking on the map, you will now have a third option to directly enter your latitude and longitude. Wind directions and butterfly flight directions on the entry form are also defined more clearly than before.
--Royce Bitzer, January 24, 2018
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