An inchworm (Family Geometridae) about 15mm long. Bernd Heinrich in "Winter World" determined that inchworms are a primary winter food item for Golden-crowned Kinglets (Regulus satrapa). The birds forage for them incessantly through the trees even on the coldest days. He collected caterpillers by rapping on the trunks of small trees and sorting amid the debris that fell to the snow below. The caterpillars, frozen solid, soon revived in his lab.