Birding Travels
In North America

Acmon Blue - Plebejus acmon
East of Hillsboro, New Mexico

In June 2016 we were hiking in Ready Pay Gulch, north of NM-152, east of Hillsboro, New Mexico, USA and found several small butterflies.  In the crop was the Lupine Blue, Icaricia lupini (or Plebejus lupini) pictured immediately above and below.

In the recent past the species determination for this butterfly has been in flux.  In previous posts, and in our photo galleries we had listed this butterfly as Acmon Blue, Plebejus acmon.  Some New Mexico references still contain information which supports this species determination, which is that used by Scott (see below) in earlier publications.

Defining the species as Lupine Blue is the systemization that Bugguide.net.  Acmon Blue is used by Butterflies and Moths of North America, the Peterson guide, and perhaps Scott (see below) in later editions adhere to.  The Peterson Field Guides - Western Butterflies by Opler and Wright list the genus as Icaricia lupini (p. 252). Wikipedia lists the species as Aricia lupini.  

The Butterflies of North America - James A. Scott - p. 411, defines this butterfly as Acmon Blue (aka Silver-studded Blue), Plebejus acmon.  If you adhere to the Lupine Blue view of the world, this is probably the subspecies texanus, of whatever the genus/species name you choose.

This species is frequently found at mid-elevations (about 5,400’ in Ready Pay Gulch).  It is a small butterfly with a wingspread of between 1.5 and 2 cm.  

This species was first described by Jean Baptiste Boisduval in 1869.  Along the way it has gone by several synonyms, including; Plebejus lupinus, Lycaena lupini, Plebejus lupini, Icaricia lupini, and Rusticus chlorina. In 2002, P. A. Opler and A. D. Warren concluded that Plebejus lupine - P. acmon represented a species complex of an undetermined number of species.  By 2003, Opler had concluded that P. acmon was monotypic and restricted to the west coast of the United States and Baja, Mexico.  Some authorities consider P. lupini to have 11 or more subspecies.  Systematics for this species are in flux.