'Desert' Black Swallowtail - Papilio polyxenes coloro
A fresh Papilio polyxenes coloro perching along Cactus Spring Trail, April 27, 2017.
'Desert' Black Swallowtail - Papilio polyxenes coloro
Here's a coloro nectaring on the same trail a week earlier, April 22, 2017.
'Desert' Black Swallowtail - Papilio polyxenes coloro
A hungry last-instar coloro larva was munching host Thamnosma montana right at the trailhead on the same hike as above.
'Desert' Black Swallowtail - Papilio polyxenes coloro
A closer look at the same caterpillar.
'Desert' Black Swallowtail - Papilio polyxenes coloro
A very cooperative Papilio polyxenes coloro at gravel along Horsethief Creek, which is down Cactus Spring Trail in Riverside Co. September 20, 2014. This one didn't move for five minutes; not my usual experience with these. These can be very small, and this one looked not much larger than a Painted Lady.
'Desert' Black Swallowtail - Papilio polyxenes coloro
This 'Desert' Black Swallowtail - Papilio polyxenes coloro - was hilltopping above Palm Springs. September 4, 2010.
'Desert' Black Swallowtail - Papilio polyxenes coloro
Small, early stage caterpillar of Papilio polyxenes coloro, probably a second instar, on host Thamnosma montana. April 15, 2011, at the Cactus Springs Trail in the Santa Rosa Wilderness.
'Desert' Black Swallowtail - Papilio polyxenes coloro
Another caterpillar of Papilio polyxenes coloro, probably a fourth instar. After this stage, the spines disappear and they become smooth - see the one above from 2017. April 30, 2019, again at Cactus Springs Trail in the Santa Rosa Wilderness.

©Dennis Walker