Euchloe andrewsi

Andrew's Marble

This butterfly was first described as a subspecies of Euchloe ausonides in 1936 from specimens collected almost exclusively from the Lake Arrowhead area, between 5000-6000' elevation. Paul Opler placed it within hyantis in a 1966 paper. Similar butterflies found at higher elevations on the east side of Big Bear Lake - esp. the north side of Sugarloaf Mountain - were assumed to be the same butterfly. But by the time the Emmels' The Butterflies of Southern California was published in 1973, lepidopterists such as Chris Henne and John Emmel had figured out that there were two distinct populations. A relatively recent paper* concluded that "[b]ecause of its phenetic distinctness and close parapatry with other E. hyantis populations, with a concomitant lack of intermediacy, we feel that E. andrewsi can be treated as a local endemic species with strong need for conservation concern and action.” Some of the visual distinctions I've learned about that distinguish andrewsi include black coloration at the dorsal wing bases; a lack of pearly luster in the ventral white areas; larger size; and a more rounded apex. The eastern Euchloe feeds mainly on Descurainia pinnata and probably Boechera pinetorum, while andrewsi mostly uses Streptanthus bernardinus.

There is a lot of information in print and on the web that probably is outdated or just incorrect concerning these butterflies, including misidentified photos and food plant information that is based on outdated assumptions. Hopefully we'll know more about these interesting populations soon.

*Werner Back, Michael A. Miller, and Paul A. Opler "Genetic, Phenetic, and Distributional Relationships of Nearctic Euchloe (Pieridae, Pierinae, Anthocharidini)," The Journal of the Lepidopterists' Society 65(1), 1-14, (1 March 2011).

Caterpillar of Andrew's Marble - Euchloe andrewsi
These caterpillars of Euchloe andrewsi were found south of Green Valley Lake in the San Bernardinos on June 25th, 2023. I actually found four of them, probably third instars.
Larva of Andrew's Marble - Euchloe andrewsi
This species eats the buds and flowers of the food plant, and I've seen it eating siliques and stems as well. This larva is actually on what I believe is Streptanthus campestris.
Larva of Andrew's Marble - Euchloe andrewsi
A week later I returned and found two mature larvae. They have a white lateral stripe that doesn't continue into the head capsule as does that of A. sara, and a purple line at the top edge of the white stripe. With lanceolata, the stripe would be yellow.
Pupa of Andrew's Marble - Euchloe andrewsi
This is the pupa, from July 12th, 2023.
Streptanthus bernardinus from the San Bernardino Mountains
Streptanthus bernardinus (Laguna Mountains jewelflower) is the main food plant for larvae of Andrew's marble.
Original description of Euchloe (hyantis) andrewsi by Lloyd Martin in 1936
Lloyd Martin described this butterfly in 1936 based on specimens collected by a Pasadena collector named Andrews. This is from the Bulletin of the Southern California Academy of Sciences 35(2):94-95.

©Dennis Walker