Moths in the genus Eupithecia are small geometrids, with characteristic long, narrow wings held out at right angles to the body. It is a very large genus, and many of the species are hard to identify. Some of the caterpillars are rather specific in their choice of foodplant, and many feed inside flowers. The caterpillar here, however, was found on the leaves of Hardhack (Spiraea douglasii), and readily accepted the leaves of willow. The moths are generally referred to as “pugs”.