This is a longish report about relatively few butterflies, so read only if you have the spare time.
Intent upon one final field trip for the season, I drove to Alpowa Summit, east of Pomeroy, on October 4. The next day was forecast to be the last of the hot ones in southeastern Washington. It dawned hazy and partly cloudy and cold, but improved from there. I continued to Clarkston, Asotin County, then south along the Snake River to Asotin and beyond. This is the extreme southeatern corner of Washington.
One mile north of Buffalo Eddy, a large, bright orange butterfly flew past me heading north. It seems likely it was either a monarch (if so, one of very few seen in Washington this year) or a viceroy. About five miles north of Heller's Bar, just beyond Captain John's Rapids 46.138403, -116.935996, a broad sandy bar above the river had three large, prime-bloom rabbitbrushes, and a number of smaller ones. They were teeming with pollinators, including Lepidoptera: many species of diurnal moths, and several each o fjuba skippers (most common), orange sulphurs, western whites, gray hairstreaks, and purplish coppers, and one each of western branded skipper, Mormon metalmark, and what I believe is a male checkered white (vouchered). The branded skipper is Hesperia colorado idaho, just a couple of hundred yards from Idaho across the Snake River.
In the same mile, there is the first of a series of three lush green seeps coming down the dramatic basalt cliffs from irrigation above on the plateau. This has been an extremely arid summer over there, but there has been a little rain recently, and there was still water in the seeps and big stands of watercress and an autumn-blooming tall aster around them. The first seep, at 46.133851, -116.940738, had cabbage whites, western whites, mylitta crescents, and a pair of worn skippers that flummoxed me at first but turned out to be Yuma skippers (see below). These I vouchered.
The second major seep is also just across the road from the first good hackberry tree pull-out, at 46.131289, -116.943254 . It had the same species minus the Yumas. I noticed immediately that a large percentage of the hackberries (Celtis reticulata), maybe half, looked dead, and many of the rest were in bad shape. Tapping them produced clouds of a tiny insect, and at first I thought it might have been a defoliating micro-moth. But they were a hatch of a very small caddis, and the trees were not actually defoliated—they simply had dead, shriveled and dried leaves. It must have been heavy stress from the extreme drought, and perhaps also from the intense hear in June.
The last large seep, at 46.125909, -116.950111, had a good stand of western giant reed (Phragmites australis, native genotype), which is the hostplant of the Yuma skipper; as well as goldenrod, on which were nectaring cabbage whites, mylitta crescents, and gray hairstreak.
After midday, now around 80 degrees F. and mostly sunny, I passed Heller's Bar at the confluence of the Snake River with the Grand Ronde River, and headed up the latter. Here I have sought hackberry butterflies (Asterocampa) many times, especially since Ray Stanford and Charles Rogers reported sightings just north and just south along the Snake. The Grand Ronde hosts many dense stands of hackberry, and lacks the fishing traffic of Heller's Bar. My own favorite grove was preoccupied by a trailer, though so I carried on to my favorite river access and a nice stretch of the small dirt road that I call "Hackberry Alley," where I may have had a sighting on one previous expedition with David Branch. This is located at 46.071120, -117.008942
I made two dramatic observations over lunch. First, over the top of a hackberry over the road, appeared a big black swallowtail! Or so it looked. But we have only small black swallowtails, and only in the spring. This was a bat! A small one, maybe a little brown or a pipistrelle. It flitted back and forth over the road, over the tree, over me, hunting, in broad daylight I saw it go for a fly, and miss. Of course, bats do sometimes hunt by day…I have seen it several times, but always in winter, never in summer or fall, or on a hot, bright day.
Second, an obvious nymphalid butterfly appeared, motoring down the middle of the road right toward me…and then right over me, and disappeared! The whole way it was in the shade of Hackberry Alley, so I didn't get the color well, but I could tell it was neither black nor orange. Nor was the flight pattern like a lady, either red admirable or other. Just before it shot over me, I got a quick image of its shape as it flapped at eye level. The forewings looked somewhat produced, which means slightly drawn out, but rounded, not angled like a falcate lady or a comma—in fact, just like a male hackberry butterfly! The size, flight, brown-gray shade, and that shape were all correct for Asterocampa. Does this mean I've seen it at last? No…I might have, but it leaves me still an agnostic…much as for Bigfoot! But it's the best I've seen yet.
I waded the stream, usually good for viceroys and various others, but too late and autumnal now. Ditto for the other spots I checked through the cooling afternoon. And so, back to Alpowa Summit, a literal "high point" for Lewis & Clark on their return journey, as for mine. The next day, October 6, came cloudless and blue, but considerably cooler. I intended to work the golden ocean of rabbitbrush all the way down the Gorge toward home, and so I did. But there was a cool wind off the Columbia. Nothing like the diversity of moths on the rabbitbrush as in Asotin, and almost no butterflies. I checked many adjacencies of rabbitbrush and Russian thistle for western pygmy blues, but no cigar!
However, at a couple of spots, I did have some final luck. At a dead-end entrance to McNary National Wildlife Refuge off SR 12 @ 46.058182, -118.859416 , there were, on rabbitbrush: orange sulphur, cabbage white, western white, and mylitta crescent.
Then, in two miles, came Madame Dorion Memorial Park, near the mouth of the Walla Walla River, right at Wallula Junction (the intersection of SR 12 and SR 730) @ 46.057506, -118.908352. There is an old-road bridge halfway across the broad WW River, and a good stand of reeds—look for Yuma here in future! And a sea of rabbitbrush. Among the whites and sulphurs, I spotted a yellow, and netted it—an Eriphyle (=western clouded) sulphur. And then on a long row, I spotted a single skipper with my binoculars, Hoping for a Sachem, I hunted and found it, and it was!—a bright male Sachem with its huge stigmata. Two species not sighted yesterday. And that was that.
Notes: The monarch, if that's what it was, would be one of very few seen in the state this year. The pair of Yuma skippers are the third record for this canyon (I found another October female years ago, and Jim Dillman has found it here since); and only the third locality for Washington. The checkered white, if confirmed by JPP, will be one of a handful of known WA records. And Asterocampa celtis, if (and when!) confirmed, would be a state record. But, as Jon Pelham wrote me: "That emperor "sighting" promotes your further questing! I hope you never capture one only so's you keep searching so hard! On the other hand, if you catch one...Hoorah! Win-win!!"
So here are the fifteen species seen—not bad for this latitude at this late date: colorado, juba, yuma, campestris, eurytheme, eriphyle, rapae, protodice (prob.), occidentalis, melinus, helloides, mormo, plexippus/archippus?, mylitta, celtis (or something!). I'll be back next summer, if it's not as stinking hot and dry as it was this year.