Species Profile: Echo Azure

As we near the end of October, most butterflies in the Pacific Northwest have died off or gone into winter diapause, although a few sightings of butterflies visiting late-blooming thistles and rabbitbrush are still being reported in some areas.  Rather than choosing one of those species to discuss today, I decided instead to look ahead to the return of warmer weather and one of the first butterflies to emerge in Spring: the Echo Azure.
Echo Azure (Celastrina echo), a.k.a. Echo Blue or Spring Azure
Description
Wingspan: 3/4 to 1 1/4 inches

Male: frosty blue dorsal with thin charcoal border and white fringe lightly checkered with gray.  Ventral is dirty white-gray with variable dark brownish-gray markings; VHW margin always marked with row of dark gray spots capped with dark gray crescents.
Female: dorsal blue is much reduced with wide brownish-gray border.
Egg: pale greenish white.
Larva: yellowish- to whitish-green, final instar has highly variable markings in shades of magenta, white and dark green.
Pupa: dirty brown with blackish blotches.

Similar Species
Ventral markings of other blue species are more black rather than brownish gray.  Lighter Echo Azures may resemble Western Tailed Blues (Cupido amyntula) that are missing tails, or Anna's Blues (Plebejus anna), but Echo Azures are deeper blue and have no orange markings or scintillae (reflective blue-green scales) on the ventral surface.

Habitat & Biology
Habitat: forests, canyons, and moist areas with flowering shrubs.
Overwintering stage: pupa.
Larval host: uses a wide variety of flowering shrubs. Snowbrush (Ceanothus velutinus) is a confirmed host on the Sinlahekin, and adults were observed near Red Osier Dogwood (Cornus sericea) but no eggs were found at that time. Other potential hosts available include Ocean Spray (Holodiscus discolor), Western Sandcherry (Prunus besseyi), Bittercherry (P. emarginata), Common Chokecherry (P. virginiana), Mallow Ninebark (Physocarpus malvaceus), Blue Elderberry (Sambucus cerulea), Red Elderberry (S. racemosa), and White Spirea (Spirea betulifolia).
Adult food source: numerous flowers, including those of host shrubs as well as violets and buckwheat; males frequently visit mud, fire pits, and scat.

Hatched egg of Echo Azure on bud cluster of Snowbrush (Ceanothus velutinus), Sinlahekin Wildlife Area, Okanogan County, WA

Echo Azure larva on Snowbrush (Ceanothus velutinus), Chumstick Mountain, Chelan County, WA

Specimens of Echo Azure (Celastrina echo) showing the wide range of variation; all of these were collected in the Sinlahekin Wildlife Area, mostly from a single location within three days of each other in May.