California’s Butterflies

El Segundo Blue

At Right: Two mating adult El Segundo Blue butterflies (Euphilotes battoides allyni).

When the El Segundo Blue (Euphilotes battoides allyni) was first described it was thought to be restricted to the El Segundo Dunes near Los Angeles International Airport (LAX) and a nearby area owned by Chevron.  Since much of the dunes had been destroyed prior to the butterfly’s description in the early 1970s it was put on the Federal Endangered Species List when the Endangered Species Act was enacted in the late 1970s. 


Other populations of the El Segundo Blue butterfly were later found on the steep north-facing slopes of the neighboring Palos Verdes Peninsula.  Some experts thought these Palos Verdes populations were not the El Segundo Blue butterfly, but the closely related Bernardino Blue butterfly.  When sympatric populations of El Segundo Blue butterflies on Eriogonum parvifolium were compared to Bernardino Blue butterflies on Eriogonum cinereum using allozymes, they were found to be distinct.  For this reason it was concluded that the El Segundo Blue butterfly on the Palos Verdes Peninsula was a distinct species from the Bernardino Blue butterfly.


In 2005 El Segundo Blue butterflies were found in Vandenberg Air Force Base.  This taxonomic decision was based on male and female genitalic characters and the fact that the butterfly is using the dune buckwheat, Eriogonum parvifolium.  Presently the only member of the Euphilotes battoides complex that uses the dune buckwheat is the El Segundo Blue.   This newly discovered population needs to be studied more thoroughly to determine the actual relationship to the El Segundo Blue.  Upon further study, it could be found that this new population may not be the El Segundo Blue butterfly, but is instead a new subspecies of the Euphilotes battoides complex.

At Left: An El Segundo Blue larva.