Acmon Blue - Plebejus acmon
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 1.1-1.4 cm. Sexually dimorphic; upperside of male deep blue to greenish-blue, female brown and sometimes with orange along veins. Uppersurface usually with black spot in forewing disk, hindwing with black scaling interior to orange aurora. Undersurface variable, off-white with pattern of black spots, hindwing submarginal orange band with iridescent blue spots, hindwing black marginal line not swollen at veins, fringes unchecked.
Many flights in the south, March to October; one flight in the north, mid-June to early July, July to early August above treeline (Scott 1986). Mainly March and April to August and September, almost all year in southern California and Arizona, June to July at high elevation and into Alberta and Saskatchewan (Glassberg 2001).Early April to early October in Oregon and Washington (Pyle 2002; Warren 2005), mid-May to mid-August in British Columbia (Guppy and Shepard 2001).
Best determined by a combination of Uppersurface usually with black spot in forewing disk, hindwing with black scaling interior to orange aurora; submarginal orange band of hindwing undersurface with iridescent blue spots, hindwing black marginal line not swollen at veins, fringes unchecked.
Southwestern British Columbia, southern Alberta and Saskatchewan south through all of western US to northwestern Mexico, east to central Great Plains (Goodpasture 1973; Scott 1986; Opler and Wright 1999; Glassberg 2001); from 1310 m to 3810 m elevation in Colorado (Scott and Scott 1978; Ferris and Brown 1981), to 2438 m elevation in Oregon (Warren 2005). In Montana, reported across the state (Kohler 1980; Stanford and Opler 1993). Mainly common but rare to uncommon east of the continental divide (Glassberg 2001).
Non-migratory; infrequent eastward dispersal occurs (Scott 1986, 1992).
A wide variety of open habitats, including oak woodland, montane conifer woodland, desert chaparral, rocky slopes and flats, prairie hills, sagebrush steppe, weedy areas, roadsides, above treeline in alpine terrain (Scott 1986; Opler and Wright 1999; Glassberg 2001; Guppy and Sheperd 2001; Pyle 2002). In Glacier National Park, Montana, reported from montane xeric meadows and above treeline in alpine terrain (Debinski 1993).
Larval food plants include Astragalus, several species of Eriogonum, several species of Lotus, Lupinus, Melilotus, Polygonum, and Trifolium flowers (Goodpasture 1974; Scott 1986, 1992; Guppy and Shepard 2001; Pyle 2002; Warren 2005). Adults feed on flower nectar (including Asclepias, Astragalus, Baccharis, Brassica, Cirsium, Eriodictyon, Eriogonum, Polygonum) and mud (Scott 1986, 2014; Warren 2005).
Females lay eggs often singly (but up to 10) on host plant leaves or flowers (Goodpasture 1974; Scott 1986, 1992). Eggs hatch in about 6 days (depending on temperature). Development from egg-laying to pupation about 28 days, adult eclosion (emergence from pupae) about 7 days after pupation. Larvae do not build nest, remain hidden in host flowers, diapause as L2 or L3 instars, are tended by ants (Aphaenogaster, Formica, Iridomyrmex) in some regions, wander off host plant to pupate in leaf litter (Goodpasture 1973; Scott 1979; Warren 2005; James and Nunnalee 2011). Males patrol throughout the day on flats or hillsides near host plants as they seek females (Scott 1975b, 1986).
- Literature Cited AboveLegend: View Online Publication
- Debinski, D. 1993. Butterflies of Glacier National Park, Montana. Occasional Papers of the Museum of Natural History, the University of Kansas, Lawrence, Kansas. No. 159: 1-13.
- Ferris, C.D. and F.M. Brown (eds). 1981. Butterflies of the Rocky Mountains. Univ. of Oklahoma Press. Norman. 442 pp.
- Glassberg, J. 2001. Butterflies through Binoculars: A Field Guide to the Butterflies of Western North America. Oxford University Press.
- Goodpasture, C. 1973. Biology and systematics of the Plebejus (Icaricia) acmon group (Lepidoptera: Lycaenidae) I. Review of the group. Journal of the Kansas Entomological Society. 46(4): 468-485.
- Goodpasture, C. 1974. Foodplant specificity in the Plebejus (Icaricia) acmon group (Lycaenidae). Journal of the Lepidopterists' Society. 28(1): 53-63.
- Guppy, C.S. and J.H. Shepard. 2001. Butterflies of British Columbia: including western Alberta, southern Yukon, the Alaska Panhandle, Washington, northern Oregon, northern Idaho, northwestern Montana. UBC Press (Vancouver, BC) and Royal British Columbia Museum (Victoria, BC). 414 pp.
- James, D.G. and D. Nunnallee. 2011. Life histories of Cascadia butterflies. Corvallis, OR: Oregon State University Press. 447 p.
- Kohler, S. 1980. Checklist of Montana Butterflies (Rhopalocera). Journal of the Lepidopterists' Society 34(1): 1-19.
- Opler, P.A. and A.B. Wright. 1999. A field guide to western butterflies. Second edition. Peterson Field Guides. Houghton Mifflin Company, Boston, Massachusetts. 540 pp.
- Pyle, R.M. 2002. The butterflies of Cascadia: a field guide to all the species of Washington, Oregon, and surrounding territories. Seattle Audubon Society, Seattle, Washington. 420 pp.
- Scott, J.A. 1975b. Mate-locating behavior of western North American butterflies. Journal of Research on the Lepidoptera 14:1-40.
- Scott, J.A. 1979. Hibernal diapause of North American Papilionoidea and Hesperioidea. Journal of Research on the Lepidoptera 18(3): 171-200.
- Scott, J.A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press, Stanford, California.
- Scott, J.A. 1992. Hostplant records for butterflies and skippers (mostly from Colorado) 1959-1992, with new life histories and notes on oviposition, immatures, and ecology. Papilio new series #6. 185 p.
- Scott, J.A. 2014. Lepidoptera of North America 13. Flower visitation by Colorado butterflies (40,615 records) with a review of the literature on pollination of Colorado plants and butterfly attraction (Lepidoptera: Hersperioidea and Papilionoidea). Contributions of the C.P. Gillette Museum of Arthopod Diversity. Fort Collins, CO: Colorado State University. 190 p.
- Scott, J.A. and G.R. Scott. 1978. Ecology and distribution of the butterflies of southern central Colorado. Journal of Research on the Lepidoptera 17(2): 73-128.
- Stanford, R.E. and P.A. Opler. 1993. Atlas of western USA butterflies: including adjacent parts of Canada and Mexico. Unpubl. Report. Denver and Fort Collins, Colorado 275 pp.
- Warren, A.D. 2005. Lepidoptera of North America 6: Butterflies of Oregon, their taxonomy, distribution, and biology. Contributions of the C. P. Gillette Museum of Arthropod Diversity, Colorado State University. Fort Collins, Colorado. 406 pp.
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