Rocky Mountain Dotted-Blue
Euphilotes ancilla (Barnes & McDunnough, 1918)
Family: Lycaenidae
Subfamily: Polyommatinae
Identification: Upperside of male is deep blue with wide black borders; hindwing orange band usually absent. Female brown with variably expressed marginal orange patch on the hindwing. Underside of both sexes is light blue-gray with black spots. Underside of forewing often suffused with smoky gray.
Wing Span: 5/8 - 1 inch (1.6 - 2.5 cm).
Life History: Dotted Blues usually stay near their host plants. Males patrol around the host plants all day to find females. Eggs are laid singly on flowers or buds; caterpillars eat flowers and fruits and are tended by ants. Chrysalids hibernate in leaf litter.
Flight: One flight; late April to early August depending on location and elevation.
Caterpillar Hosts: Various Eriogonum species, especially Sulphur-flower.
Adult Food: Flower nectar, especially from Eriogonum.
Habitat: Sun-exposed rocky slopes and flats with host plant colonies.
Range: Washington south to California and southern Alberta and Saskatchewan south through rockies and high plains to Wyoming, Colorado, Utah, and northwestern New Mexico.
Conservation: Not required for the species, but rare subspecies in Nevada require survey and assessment of threats from alien weeds.
NCGR: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery. Subspecies shieldsi Austin and purpura Austin of Nevada are of high conservation concern because of their local nature and possible threat from invasive alien weeds such as cheatgrass.
Management Needs: Conserve habitats for rare subspecies and maintain host plant populations.
Comments: NULL
Verified Sightings
Displaying 1 - 24 of 238 verified sightings
Observation date: Jul 06, 2020
Submitted by: meister
Region: Garfield County, Colorado, United States
Verified by: mikefisher
Verified date: Nov 08, 2020
Observation date: Jun 23, 2020
Submitted by: Dwaine Wagoner
Region: Natrona County, Wyoming, United States
Verified by: J_Martineau
Verified date: Jun 25, 2020
Observation date: Jun 01, 2020
Submitted by: joeleahy
Region: Jefferson County, Colorado, United States
Verified by: A_baldini
Verified date: Jun 06, 2020
Observation date: Jul 21, 2019
Submitted by: stevecary
Region: Gilpin County, Colorado, United States
Verified by: mikefisher
Verified date: May 30, 2020
Observation date: Jul 19, 2019
Submitted by: stevecary
Region: Gilpin County, Colorado, United States
Verified by: mikefisher
Verified date: May 30, 2020
Observation date: Jul 11, 2019
Submitted by: stevecary
Region: Lake County, Colorado, United States
Verified by: mikefisher
Verified date: May 30, 2020
Observation date: Jun 29, 2019
Submitted by: A_baldini
Region: Larimer County, Colorado, United States
Verified by: mikefisher
Verified date: Oct 04, 2019
Observation date: Jun 16, 2019
Submitted by: A_baldini
Region: Larimer County, Colorado, United States
Verified by: mikefisher
Verified date: Sep 21, 2019
Observation date: Jul 25, 2019
Submitted by: ncrosbyrd
Region: Teton County, Wyoming, United States
Verified by: J_Martineau
Verified date: Sep 04, 2019
Observation date: Jul 18, 2019
Submitted by: ASchmierer
Region: Carbon County, Wyoming, United States
Verified by: J_Martineau
Verified date: Sep 04, 2019
Observation date: Jul 28, 2019
Submitted by: A_baldini
Region: Larimer County, Colorado, United States
Verified by: A_baldini
Verified date: Aug 18, 2019
Observation date: Jun 30, 2019
Submitted by: edz111
Region: Boulder County, Colorado, United States
Verified by: A_baldini
Verified date: Jul 03, 2019
Observation date: Jun 24, 2019
Submitted by: dsperanza
Region: Powell County, Montana, United States
Verified by: J_Martineau
Verified date: Jun 26, 2019
Observation date: Jun 25, 2006
Submitted by: hydapse
Region: Park County, Montana, United States
Verified by: J_Martineau
Verified date: Apr 08, 2019
Observation date: Jul 21, 2008
Submitted by: hydapse
Region: Park County, Wyoming, United States
Verified by: J_Martineau
Verified date: Feb 07, 2019
Observation date: Jun 06, 2018
Submitted by: J_Martineau
Region: Sublette County, Wyoming, United States
Verified by: J_Martineau
Verified date: Dec 20, 2018
Observation date: Jun 25, 2018
Submitted by: dsperanza
Region: Montana, United States
Verified by: J_Martineau
Verified date: Jun 28, 2018
Observation date: Jun 24, 2016
Submitted by: Joyjoy
Region: Grand County, Colorado, United States
Verified by: mikefisher
Verified date: Jul 16, 2016
Observation date: Jul 12, 2015
Submitted by: ncrosbyrd
Region: Gunnison County, Colorado, United States
Verified by: azukoff
Verified date: Mar 07, 2016
Observation date: Jun 22, 2013
Submitted by: Larry S Price
Region: Boise County, Idaho, United States
Verified by: CA Ivy
Verified date: Jan 24, 2016
Observation date: Jun 09, 2013
Submitted by: HHowell
Region: Teton County, Wyoming, United States
Verified by: CA Ivy
Verified date: Jan 23, 2016
Observation date: Jul 10, 2015
Submitted by: ncrosbyrd
Region: Gunnison County, Colorado, United States
Verified by: mikefisher
Verified date: Jan 18, 2016
Observation date: Jun 22, 2015
Submitted by: J_Martineau
Region: Teton County, Wyoming, United States
Verified by: J_Martineau
Verified date: Dec 10, 2015
Observation date: Jul 10, 2015
Submitted by: ncrosbyrd
Region: Gunnison County, Colorado, United States
Verified by: mikefisher
Verified date: Nov 22, 2015
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