Friday, June 28, 2013

Plume Moth Experts Hard to Come By

Yarrow Plume Moth (c) John Ashley
An adult "Yarrow Plume Moth" on common yarrow flowers at Wayfarers State Park near Bigfork, Montana
This unusual moth was fluttering between flowers and grass stems last week at Wayfarers State Park, near Bigfork along the eastern shore of Flathead Lake. It's a rare plume moth - maybe a geranium plume moth (Amblyptilia pica), like the one I found last summer in Glacier National Park. If so, then this would be only the sixth record fo any plume moth in Montana, and just the second geranium plume moth. Unfortunately, there don't appear to be very many plume moth experts out there, so I'm still working on the species identification.

Plume moths are unique in that they often roll their wings when perched. Normally, this makes them form a "T" shape, but this moth has it's abdomen curled under to probe the yarrow flowers (Achillea millefolium). Or perhaps it was laying eggs - I'll have to check that area more often!

8/23/13 UPDATE. Well I was in the right neighborhood but at the wrong address. This plume moth has just now been identified as a not-so-rare Gillmeria pallidactyla. I've found it referred to as the "Yarrow Plume Moth," due to its close association with its primary food plant, common yarrow (Achillea millefolium). Their caterpillars live inside the yarrow stems and hibernate in the yarrow roots. Come springtime, the larvae mine the young shoots before moving outside to pupate on the yarrow leaf or stem. Still a cool moth, regardless of its rarity.