While it’s nearly impossible to follow a hairstreak’s rapid flight, flitting from side to side or in circles, a stop at a “fueling station” provides an opportunity for a closer look. But, you’re unlikely to see their upperside, as most hairstreaks perch with wings closed. The Sylvan’s upperside is gray-brown or reddish with a blue sheen, with a small orange patch at the lower edge of the hindwing (females have a yellowish tinge). They range from Western Canada south through California, and to New Mexico in areas where willows grow (streamsides, ditches, marshes, foothill meadows, canyons, valley bottoms in Montana). There is one brood per year. Females lay eggs on willow stems and caterpillars hatch in spring and begin feeding on the newly emerged leaves.
Photo by: Glenn Marangelo on 8/16/21 near Condon, MT