Mitoura siva near chalcosiva (San Bernardino Mtns.)

Juniper Hairstreak

This butterfly can look very much like nelsoni, but they tend to be more boldly marked. The host is western juniper, Juniperus occidentalis, while nelsoni uses incense cedar as host. At Onyx Summit and along the Sugarloaf Trail down to Wildhorse Meadows, this butterfly can be easily found taking nectar on flowers. Thanks to John F. Emmel for help with this butterfly. Dr. Emmel says some specimens of this butterfly show intergradation with nelsoni. Perhaps what we're witnessing is an early stage of speciation, with one entity adapted to juniper and showing slightly bolder markings than the closely-related entity nearby adapted to incense cedar. Emmel says of near chalcosiva:

They occur in areas of Juniperus occidentalis in the San Bernardino Mts., southern Sierra Nevada around Kennedy Meadows, Loon Lake area west of Lake Tahoe, and in large stands of J. occidentalis in Lassen and Modoc counties. There is Calocedrus nearby these stands, and in those Calocedrus areas you get the typical nelsoni phenotype. Some of the specimens from Onyx Summit show intergradation between the two entities. Likewise in Modoc County the two hosts can be intimately sympatric and have the whole gamut of underside pattern from nelsoni to chalcosiva. I have beaten larvae from Juniperus occidentalis in Modoc County which were typical "near chalcosiva". (Pers. comm.)

These overwinter as papae in the ground litter beneath the host Junipers. Larvae eat fresh growth.

A juniper hairstreak from the eastern San Bernardino Mountains
This is a western juniper-feeding hairstreak - Mitoura siva near chalcosiva - at Wildhorse Meadow, southeast of Big Bear Lake. June 28, 2013. These can look exactly like Mitoura nelsoni, but many of them - such as this one - are more boldly colored.
A juniper hairstreak from the eastern San Bernardino Mountains
Another Mitoura siva near chalcosiva from the area, this time along the road to Wildhorse Meadows (2N93), June 2, 2017.
Western juniper - Juniperus occidentalis from the eastern San Bernardino Mountains
The host for this butterfly is western juniper, Juniperus occidentalis.
Western Juniper - Juniperus occidentalis from the eastern San Bernardino Mountains
Several Juniperus occidentalis at Onyx Peak, roughly 8450 feet elevation on Highway 38 southeast of Big Bear Lake.

©Dennis Walker