Search Field Guide
Advanced Search
Montana Field Guide

Montana Field Guides

Reakirt's Blue - Echinargus isola


Global Rank: G5
State Rank: SNA

Agency Status
USFWS:
USFS:
BLM:


 

External Links





 
General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.0-1.2 cm. Lower forewing margin looks clipped. Uppersurface of male blue, of female dusky with blue basally; both sexes with two or three dark spots on trailing margin of hindwing (in anal angle). Undersurface of forewing with arced postmedian row of five or six prominent black spots ringed with white, hindwing with smaller gray and white spots, bars, chevrons, with black and silver spots (two small, one large) in anal angle and sometimes with pale orangish halos.

Phenology
Many flights; all year in Texas, April to October in California, mid-May to October in Colorado, April to September in Illinois (Scott 1986). Mainly March to October (Glassberg 2001).

Diagnostic Characteristics
Best determined by combination of the uppersurface of both sexes with two or three dark spots on trailing margin of hindwing (in anal angle); undersurface of forewing with arced postmedian row of five or six prominent black spots ringed with white, hindwing with black and silver spots (two small, one large) in anal angle and sometimes with pale orangish halos.

Range Comments
Resident in southwestern US from southern California, southern Arizona and New Mexico, southern Texas, south through Mexico to Costa Rica. Vagrant north to Washington, Idaho, Saskatchewan, upper Midwest in southern Great Lakes region, east to Mississippi River region (Opler and Wright 1999); to 3110 m elevation in southern Rocky Mountain states (Brown 1957; Ferris and Brown 1981); 1311 m to 3805 m elevation in Colorado but mostly below 2804 m (Scott and Scott 1978), 2134 m to at least 2896 m elevation in Wyoming (Nabokov 1953). In Montana, no reports through 1993 (Kohler 1980; Shepard and Opler 1993), but reported since in Silver Bow County (no details available; reported as recently as 2013 in Natrona County, Wyoming). Common to abundant from Texas to Arizona, uncommon to common elsewhere (southern Nevada and Utah, Colorado, Nebraska), vagrant northward (Glassberg 2001).

Migration
Migratory; annually moving northward from northern edge of resident range in Texas, New Mexico, Arizona, southern California (Scott 1986; Pyle 2002).

Habitat
Open areas, weedy fields, pastures, desert thorn-scrub, waste ground, vacant lots, watercourses, moist meadows, mud flats, open woodlands, "hot hillsides" (Nabokov 1953; Emmel 1964; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002). Habitat in Montana not described but probably similar.

Food Habits
Larval food plants include Acacia, Albizzia, Amorpha, Astragalus, Coronilla, Dalea, Desmanthus, Glycyrrhiza, Indigofera, Lotus, Medicago, Melilotus, Mimosa, Oxytropis, Prosopis, Rhynchosia, and Trifolium (Ferris and Brown 1981; Scott 1986, 1992, 2006). Adults feed on flower nectar (including Achillea, Astragalus, Berteroa, Chrysothamnus, Cirsium, Eriogonum, Glycyrrhiza, Gutierrezia, Helianthus, Heterotheca, Humulus, Hymenopappus, Hymenoxys, Lavandula, Lesquerella, Liatris, Limonium, Lupinus, Medicago, Melilotus, Mertensia, Nepeta, Perovskia, Polygonum, Psoralea, Rhus, Rorippa, Sedum, Solidago, Sphaeralcea, Symphyotrichium, Tagates, Thlaspi, Trifolium) and mud (Scott 1986, 2014).

Reproductive Characteristics
Females lay eggs singly on host plant flower buds. Limited information on larval development. Larvae eat host plant flower buds, flowers, fruits, sometimes young leaves, build no nest, are tended by ants (Tapinoma reported in Colorado), exhibit no diapause (overwintering) at any stage in captivity, adults eclose (emerge from pupae) in about 10 days in captivity (Scott 1986, 1992, 2006). Males patrol erratically throughout the day over flats and in meadows near larval host plant in search of females (Scott 1975b, 1986).

References
Login Logout
Citation for data on this website:
Reakirt's Blue — Echinargus isola.  Montana Field Guide.  .  Retrieved on , from