Tuesday, November 19, 2013

A Rare Fall Visitor

'Eupsilia fringata' moth (c) John Ashley
Adult Eupsilia fringata moth
Last summer I stayed up past 1 AM for about two weeks straight, photographing moths, because one or two new species kept showing up every night to feed my fascination. Sleep deprivation was taking a toll, so with some trepidation I asked Montana's moth expert, "How late in the year do you photograph moths?" October, he replied. It's gonna' be a long fall, I thought.

Fast-forward past the fall and into early winter in western Montana. Sure enough, most of the moths petered out in early October, but I still saw a few flying around on rare nights when the temps stayed above freezing. But now I only saw moths fluttering across the beams of my car headlights, and no one showed up at my lonely porch lights any more.

Some nights I forgot to turn the porch lights on. Or, well aware that I'm turning into a doddering and forgetful old man, my wife would follow behind me and turn the porch lights back off. Week after week went by without any moths showing up.

Then suddenly, a faint tap on the door!

After not seeing any moths in the yard for over a month, one chestnut-brown adult made a surprise appearance on the sliding glass door, next to the porch light. I offered it temporary indoor housing - a glass jar in our 'fridge - for the night and photographed it the next day. Through this year I've closely examined several hundred moths of several dozen species. I could see that my late visitor was different from any moth I'd seen before, but it still just looked like a handsomely-patterned something-or-other-with-wings. Keying out moth species is a talent I sorely lack.

'Eupsilia fringata' moth observation records (c) MPG
'Eupsilia fringata' moth observation records
I turned in the photos and observation report. What came back was like opening an early Christmas gift. I had been honored with a very rare visitor indeed. Eupsilia fringata (no common name) is a type of Sallow moth with 9 or 10 related species in North America, including just a few here in the west. And by my unofficial count, Eupsilia fringata has only been documented 10 times in the past 97 years (since its designation as a species in 1916), with seven records from California and one each from Idaho, Washington and British Columbia. It's never been reported in Montana before now.

So far, we know that the adults emerge from their pupal cases in fall and fly briefly before overwintering as adults. Come spring, the adults will mate, lay eggs and die. The summer caterpillars feed on forbs (aster and goldenrod) and woody plants (willows and roses), before resting in a pupal state and morphing into fall adults. Adults are nocturnal and will come to lights - e.g. my back porch lights.

That's about all that the collective "we" knows about this species.

Tonight I peered out through our sliding glass door to watch fat snowflakes swirl and flutter around in invisible eddies - fying a lot like moths, actually. Moth-ing is an unusual hobby, I'll admit, but still I can't wait for my next moth-ly visitor to make a surprise appearance next spring. "Till then, I'll try to catch up on some sleep.

Moths of the Pacific Northwest
Butterflies and Moths of North America