Euphilotes ancilla

(Barnes & McDunnough, 1918)

Rocky Mountain dotted blue, Ancilla Blue

Euphilotes ancilla, commonly known as the Rocky Mountain dotted blue or Ancilla Blue, is a small in the Lycaenidae. First described by Barnes and McDunnough in 1918, it inhabits sun-exposed rocky slopes and flats in western North America. The has a documented wingspan of 17–23 mm and exhibits a close ecological relationship with Eriogonum plants.

Euphilotes ancilla by (c) Pacific Southwest Region U.S. Fish and Wildlife Service, some rights reserved (CC BY). Used under a CC-BY license.

Spring Mountains dark blue early (Euphilotes ancilla purpura) (8045259696) by Pacific Southwest Region from Sacramento, US. Used under a Public domain license.

Pronunciation

How to pronounce Euphilotes ancilla: //juːˈfɪloʊtiːz ænˈsɪlə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Euphilotes by combination of: small size (17–23 mm), Rocky Mountain and high plains distribution, and association with Eriogonum plants. Orange marginal spots on hindwing undersides help separate from similar blues. Precise identification may require examination of genitalia or geographic context.

Images

Appearance

Small with wingspan 17–23 mm. Upper wing surfaces blue with dark marginal markings and orange marginal spots on hindwings, characteristic of 'dotted blue' pattern. Undersides grayish with black spots and orange marginal markings. Sexually dimorphic with males showing brighter blue coloration.

Habitat

Sun-exposed rocky slopes and flats with colonies of plants. Occupies open, dry in montane and high plains environments where Eriogonum establish.

Distribution

Western North America: Washington south to California; southern Alberta and Saskatchewan south through the Rocky Mountains and high plains to Wyoming, Colorado, Utah, and northwestern New Mexico.

Diet

Larvae feed on various Eriogonum , with documented preference for sulphur-flower (Eriogonum umbellatum). diet not specified in available sources.

Host Associations

Eriogonum umbellatum - larval food plantsulphur-flower; primary
Eriogonum - larval food plantvarious

Similar Taxa

Euphilotes enoptesSynonym or closely related ; taxonomic status requires verification. GBIF lists E. ancilla as synonym of E. enoptes, while other sources maintain separate species status.
Other Euphilotes speciesShare 'dotted blue' pattern and similar ; distinguished by geographic range and plant specificity.

More Details

Taxonomic Note

Taxonomic status disputed: GBIF treats E. ancilla as synonym of E. enoptes, while iNaturalist and NCBI maintain as separate . Further taxonomic research needed to resolve status.

Observation Record

iNaturalist documents 857 observations, indicating moderate citizen science detection and potential research utility for distribution studies.