Subject: Hibernating Moths
Location: Seattle WA
February 21, 2013 10:33 pm
I was cleaning the Garage, and when I opened the barbecue grill (to fix the handle) I found that it had become a ”den of choice” for hibernation. I think these are Ectropis crepuscularia – Small Engrailed. There are a lot of them, dozens, all through the garage, and they move only very slowly, but I thought this grouping amusing.
Dear George from Washington,
These are Geometrid Moths in the family Geometridae. They are also commonly called Measuring Worm Moths or Inchworm Moths. We located on JSTOR an online article called Bat predation and flight timing of winter moths, Epirrita and Operophtera species (Lepidoptera, Geometridae) by Mats G. E Svensson, Jens Rydell and Richard Brown, when we searched for “hibernating Geometrids.” We then searched those names and found additional information, but the photos are all of rather drab and unremarkable looking moths shaped similarly to your beauties, but without the intricate markings on your moths. These must be hibernating male Winter Geometrid Moths, and we don’t really know how to tell them apart for certain based on the markings found in photos of individuals online. BugGuide has some pictures of several species from the genus Operophtera found in North America and all three species are found along the West Coast. The markings on the Espirrita species pictured on BugGuide are more defined, but different from the markings on your moths. We love your photo. We rotated it and cropped it to a square prior to sizing for the internet. Moth PHotographers Group has nice photos of the Autumnal Moth, but they do not look like your moths.