White M Hairstreak

“It’s a White M!” is a phrase I dream of crying out every year. Unfortunately, it doesn’t happen very often, and my wife Sandy had never heard me say it—until yesterday. The White M Hairstreak (Parrhassius m-album) is one of the holy grails for Indiana butterfly watchers. Prior to yesterday, I had seen four individual White Ms in Indiana in 25 years, and all were brief encounters—the individual visiting one or two flowers, giving me a view just long enough for an identification to be made, and then disappearing.

The White M Hairstreak (named for the white M–which could also be seen as a W–on its hindwing), lives in the forest canopy, and rarely descends to our level for nectar. It is superficially similar to the common Gray Hairstreak, but larger and browner on the underside, and its orange patch on the hindwing tends to be more reddish. White Ms also usually have a lone white mark near the center of the inner edge of their hindwing, which the Gray Hairstreak lacks. The upperside of the Gray Hairstreak is charcoal gray with orange spots at the base of the tails. The White M, however, is an incredible iridescent blue above, visible if sunlight strikes the wings, and usually seen as it flutters back up into the canopy.

White Ms occur across most of the eastern United States and are usually found in the vicinity of oaks (Quercus), their larval host. Basswood (Tilia americana ) is also occasionally used. There are three flights each year in our area, with adults appearing in early spring, mid-summer, and fall. In the southern states, they can be seen at virtually any time of year. The four White Ms I had seen previously in Indiana were in Owen, Parke, and Harrison Counties. The Parke County individual was seen on a butterfly count in July with a friend, the others were seen when I was alone. My most recent sightings had both occurred in early spring in Harrison County at The Nature Conservancy’s Buena Vista Glade.

Sandy had never seen a White M. During a visit to Florida a few years ago we planned to visit a location where White Ms had been recently observed, but it was pouring rain. No White Ms. Last spring we visited Buena Vista Glade—supposedly to see Cobweb Skippers—but really looking for White Ms. No White Ms (nor Cobweb Skippers!). Last summer we visited Pigeon Mountain in northwestern Georgia, a very reliable location for White Ms in the fall, but the only time we could visit was in late August, and we were probably a week early. No White Ms. When the subject of White Ms would occasionally come up, Sandy would say, “Oh, they don’t exist.”

Yesterday, April 2, began cool and cloudy, but the clouds broke about noon shortly before we arrived at Allens Creek State Recreation Area, on the south side of Lake Monroe in south-central Indiana. We often visit Allens Creek in the spring. It is an exceptional spot for spring butterflies, including Zebra Swallowtail, Falcate Orangetip, Henry’s Elfin, and Juniper Hairstreak. Initially our only lepidopteran company were the hordes of duskywings which appear in spring (and which, coincidentally, also use oaks as larval hosts). We identified both Juvenal’s and Sleepy Duskywings, the two most common duskywings in our area. About 45 minutes down the trail, Sandy saw a hairstreak. She got a brief look, then it disappeared. She was certain it was a Gray Hairstreak. I said, “Probably true, unless it was a White M.” She groaned. White M was perhaps more likely, given the wooded habitat, but Sandy didn’t see any blue on the upperside as it flitted away. But the way it was seen briefly and then disappeared reminded me all too much of a White M….

About a half hour later we arrived at an opening in the woods where there is a stand of young Eastern Red Cedar in a field. We had often seen Juniper Hairstreaks in the cedars (their larval host). As I was walking through the field I kicked up a small, dark butterfly which I initially thought was another duskywing but the flight pattern was a little different. It finally landed on some grass and I realized it was an Eastern Pine Elfin. I had seen these elfins a few times previously at this same spot. Each time the individual didn’t stick around long, and this one didn’t either. Sandy just got a glimpse of it as it flew off. We continued to look around the field, hoping to find the elfin again. We began to study a patch of pussytoes (Antennaria spp.), a low-growing, white, spring-blooming member of the Aster Family (Asteraceae). We had seen Juniper Hairstreaks nectaring on those pussytoes in past years, and we soon found one. We were enjoying its incredible green color (the only green butterfly in Indiana), when we caught a glimpse of another hairstreak behind it. I got my binoculars on it and was stunned. I yelled, “Sandy, look at that hairstreak, RIGHT NOW!!! It’s a White M!!”

Unlike all my other experiences with White Ms, this one stuck around–for over an hour–posing for many photos. Sandy was even able to call a few friends (who fortunately were already on their way to Allens Creek) and they were also able to see it. It was an odd individual—on its right side it appeared freshly emerged, but its left pair of wings were ripped all along the outer edge. About a half hour later another, much smaller individual appeared. It was very fresh. I got a few photos of it, then a jumping spider grabbed it! I tried to rescue it, but to no avail. A third individual appeared a little while later. It was also fresh, but a bit browner in color and its white markings were slightly subdued (see the photo at the beginning of this blog). All the time we were watching the White Ms the Juniper Hairstreaks continued to beg for our attention. Most were gorgeous, fresh individuals. A couple Gray Hairstreaks also appeared. An American Lady also occasionally visited the pussytoe patch, looking for a place to lay her eggs.

All in all, an incredible experience, and one not to be forgotten!  For a few glimpses of the blue on the upperside of the wings of this stunning hairstreak, watch the video below, which I shot yesterday at Allens Creek. I slowed part of the clip to provide a slightly better view.