by Steven J. Cary and Michael E. Toliver
The Gossamerwings (Lycaenidae). New Mexico has more than 50 Lycaenids in three subfamilies: Coppers, Hairstreaks and Blues. All are small, but many have bright colors or intricate patterns. Because of narrow ecological needs, finding members of this group can be both challenging and rewarding. During immature stages, most Lycaenids exhibit mutualistic relationships with ants, called myrmecophily.
The Blues (Lycaenidae: Polyommatinae). The Blues are small, complex, fascinating butterflies. Color patterns in this subfamily typically include a camouflaged underside and a bright, iridescent blue upperside that is dulled in females. Blues exhibit myrmecophily – a mutualistic (or in some cases predatory!) relationship with ants in the family Formicidae. Larvae of Blues secrete yummy fluids; ants farm the larvae – as they do aphids – protecting them from parasitoid wasps and flies in order to harvest the fluids. Several groups or complexes with this subfamily continue to confound taxonomists. New Mexico has more than 20 species of Blues and the exact count is surprisingly hard to determine!
- Cyna Blue (Zizula cyna)
- Western Pygmy-blue (Brephidium exilis)
- Marine Blue (Leptotes marina)
- Square-spotted Blue (Euphilotes centralis)
- Ellis’ Blue (Euphilotes ellisii)
- Spalding’s Blue (Euphilotes spaldingi)
- Rita Blue (Euphilotes rita)
- Stanfords’ Blue (Euphilotes stanfordorum)
- Pallid Blue (Euphilotes pallescens)
- Arrowhead Blue (Glaucopsyche piasus)
- Silvery Blue (Glaucopsyche lygdamus)
- Echo Azure (Celastrina echo)
- Eastern Tailed-Blue (Cupido comyntas)
- Western Tailed-Blue (Cupido amyntula)
- Ceraunus Blue (Hemiargus ceraunus)
- Reakirt’s Blue (Echinargus isola)
- Acmon Blue (Icaricia acmon)
- Lupine Blue (Icaricia lupini)
- Greenish Blue (Icaricia saepiolus)
- Boisduval’s Blue (Icaricia icarioides)
- Arctic Blue (Agriades glandon)
- Melissa Blue (Plebejus melissa)
Zizula cyna (W. H. Edwards 1881) Cyna Blue (updated May 8, 2022)
Description. Tiny Cyna is as small as the Western Pygmy Blue – our two most diminutive butterfly species. Cyna wing markings resemble those of the larger Echo Azure: undersides are pale gray with dark spot bands and submarginal chevrons. Cyna is blue above with a wide dark margin. Range and Habitat. Zizula cyna breeds from South America north to Mexico and south Texas. Its appearance in New Mexico is rare and accidental, when adults occasionally expand or diffuse northward in summer. Never expected, it has turned up a few times near our southern border (counties: Ed,Hi,Lu,Ot), straying up to 8000’ in the Sacramento Mountains. Life History. Nothing is reported about its life history in the literature, but larvae probably eat legumes (Fabaceae). Flight. Our records span June 21 to September 23. Adults fly near the ground in gullies and valley bottoms, seeking nectar. Comments. Zizula cyna may on occasion establish temporary breeding colonies in southern New Mexico, but they cannot survive our winters.
Brephidium exilis (Boisduval 1852) Western Pygmy-Blue (updated May 10, 2022)
Description. Our smallest butterfly has stubby forewings. Western Pygmy-Blue is gold-brown above with iridescent blue basal scaling. The hindwing above has a row of submarginal black spots, occasionally supplemented with a white patch or two. The hindwing below has four black spots pupiled with iridescent gold at the margin. Range and Habitat. Brephidium exilis is resident from South America north to the southwest US. Small as it is, each year it invades areas far north of where it can successfully overwinter, sometimes as far north as Montana and Idaho. It is reported from most of New Mexico (all counties except Un), but it breeds regularly only in southern New Mexico or at low elevations. Northern New Mexico observations probably represent strays or late season offspring. Life History. Larvae feed on plants in the Chenopodiaceae, including Atriplex canescens (four-winged saltbush; Chenopodiaceae), Kali tragus (Russian thistle aka tumbleweed; Amaranthaceae) and other plants that inhabit disturbed areas, roadsides and saline soils. Flight. Two or three generations are completed in southern New Mexico, where adults may be found year-round in suitable weather. Summer wanderers to northern New Mexico may produce a round or two of offspring before winter cold kills all. Brephidium exilis seems to be expanding its breeding range northward and upward, notably along highways that are salted in winter. Extreme early and late dates here are January 8 and December 18. Comments. Our populations are the nominate subspecies. “Yesterday, walking to the Agricultural College, I found a bush with ants running in numbers over the twigs. Looking to see what they were after, I came across a larva and then another. Presently I saw that the bush was swarming with them, only they were so perfectly concealed by their colour that I should not have noticed them except for the ants; . . . flying about the bush were many of the Exilis butterflies” T. D. A. Cockerell (1894) did not say what the plant was, but our money is on four-winged saltbush.
Leptotes marina (Reakirt 1868) Marine Blue (updated May 17, 2022)
Description. Leptotes marina’s striped underside countenance is created by alternating white and gray-tan stripes paralleling the wing margins. There are one or two dark spots near the hindwing tornus. Males are gold-brown above with an iridescent blue sheen. Females are largely brown above with a basal bluish sheen and brown stripes, echoing the stripes on the ventral surface. Females also have distinct “eyespots” near the anal angle dorsally, again echoing what appears on the ventral surface. A related species, the Cassius Blue (Leptotes cassius) is much whiter on the ventral surface, with greater extent of white at the anal angle of the FW. Cassius has been erroneously reported from NM, but it may eventually be found as a stray, particularly in the SE part of the state. Range and Habitat. Marines Blues are native to Central America, Mexico and the southwest US. An effective wanderer despite its small size, it is recorded north as far as the Great Lakes. It occurs throughout New Mexico (all counties). It had been uncommon in northern parts of New Mexico or above 8000′, but in some years they are so abundant as to suggest one or more generations of breeding. Life History. Larvae eat a variety of legumes (Fabaceae) including common natives such as mesquite (Prosopis spp.) and routine weeds such as alfalfa (Medicago sativa). Flight. Adults are reported in southern New Mexico from March 23 to November 26, suggesting at least two generations per year, perhaps even year-round flight when weather is favorable. Numbers peak in early summer, but Leptotes marina seems scarce after August. In northern New Mexico it is recorded mostly in May to July. Adults are commonly seen at nectar (e.g., Amorpha, Acacia, Asclepias), moist earth and animal dung. Comments. Our oldest report of Leptotes marina was collected by University of Kansas Professor Francis Huntington Snow in Gallinas Canyon west of Las Vegas (SM) in July or August 1882.
Euphilotes Mattoni  Buckwheat Blues
Larvae of this western genus eat only flowers and fruits of wild buckwheats (Eriogonum species; Polygonaceae), and some species seem quite loyal to their host buckwheat(s); away from which adults rarely wander far. They bask on the buckwheat, nectar at it, perch on it, patrol for mates from it, and overnight within it. If you have not found the buckwheat you will not find the buckwheat blues. Finding the buckwheat can be as easy as checking roadcuts because many buckwheats love to colonize roadcuts.
Sizes, colors and markings of all Euphilotes follow the same basic plan, as you will see below. The submarginal hindwing orange band lacks the black spots with scintillating blue sparkles that are typical of Icaricia acmon or I. lupini. Identifying an individual butterfly or population in the field or from photographs can be challenging because it often requires knowledge of the host buckwheat, its flight season, wing marks and genitalia (impossible to examine in the field). Even then, some doubt can remain due to the multitude of named forms. A solitary photo, no matter how good, or a specimen unlinked to its buckwheat, are usually insufficient to determine identity. If you are taking photos, try to get good shots of males and females, topside and bottom side; and the buckwheat.
Evolution of these similar taxa likely resulted from loyalty to larval hosts and seasonal differences in bloom times and flight times during post-pluvial isolation of >250 species and forms of Eriogonum. This plant group was elucidated by Reveal (1969). Its complex of butterfly herbivores is under study (e.g., Pratt and Emmel 1998) and will continue to be studied for some time before a good understanding is reached, possibly forever. Taxonomic levels at which to sort these various named entities (e.g., species vs subspecies, and then which species does each subspecies belong with) remain unclear, or at best a matter of opinion and disagreement among experts.
What is known about Dotted Blues in New Mexico is anchored by three taxa and their host buckwheats, wherever those buckwheats occur in good numbers. Learn these buckwheats and you will make a good start:
- Antelope Sage (Eriogonum jamesii v. jamesii) hosts Square-spotted Blue (Euphilotes centralis) across much of the state, usually on exposed or disturbed, south-facing slopes from 6000 to 8500 feet elevation.
- Redroot Buckwheat (Eriogonum racemosum) hosts Spalding’s Blue (Euphilotes spaldingi) across much of northern and central New Mexico, usually in dry meadows from 6500 to 8500 feet elevation.
- Wright’s Buckwheat (Eriogonum wrightii) hosts Rita Blue (Euphilotes rita) in semi-arid grasslands of eastern, central, southern and southwestern New Mexico, typically 5000 to 7000 feet elevation.
Beyond those three known players, many questions remain to be answered about which dotted blue is associated with which buckwheat. Field observations or photos should always include the buckwheat. Because the buckwheats are so complex, identification by a qualified botanist is highly recommended.
Euphilotes centralis (W. Barnes & McDunnough 1917) Central or Square-Spotted Blue (updated July 24, 2022)
Description. Males are deep blue above with a compact, pink-orange aurora near hindwing tornus. Dorsally, the black margin on the forewing is wide, often 20% of the wing radius. Grey/brown females have a hindwing submarginal orange band. A gray/white ventrum has black dots that are smeared on the forewing. Wing fringes are checkered. The submarginal hindwing orange band is relatively narrow compared to other Euphilotes, occupying only about half the available space. Range and Habitat. Central Blues live in shrublands and savannas of the western US, including New Mexico’s major uplands and escarpments (counties: Be,Ca,Ci,Co,Gr,Gu,Ha,Li,LA,MK,Ot,Qu,RA,Sv,SM,SF,Si,So,Ta,To,Un), 5000 to 9000′. Life History. Larvae eat antelope sage (Eriogonum jamesii var. jamesii) and this association is often enough to confirm identity of this butterfly. Flight. Adults fly in mid-summer, generally between June 21 and August 27; lower elevation colonies (Gu,Qu) fly later, into September. Comments. Taxonomically, this butterfly is pretty well understood. The only ongoing debate is whether centralis is a full species as per Pelham (2021) or a subspecies within Euphilotes battoides (Behr 1867) as treated by Ferris and Brown (1980), Brock and Kaufman (2003) and Glassberg (2017). If you like the former approach, as we do at present, then our populations are the nominate subspecies, Euphilotes centralis centralis. More Comments. There are a handful of unsubstantiated reports of Euphilotes ancilla (probably ssp. barnesi Opler & M. Fisher 2009) from northern NM which may be centralis, genuine ancilla, or a completely different species. Those records are from Co,Sv,SJ & SF; further research will tell (we hope). E. ancilla larvae feed on Eriogonum umbellatum, which is extremely scarce in northern NM. Adults of ancilla emerge earlier than centralis, though their flight periods may overlap.
Euphilotes ellisii (Shields 1975) Ellis’ Blue (updated May 16, 2022)
Description. Compared to Central Blues, Ellis’ males are a much paler blue above with a narrower black border. Females may be lighter brown above with a wider orange band. It is more important to be able to distinguish it from ‘Colorado’ Rita Blue, with which it often flies in northwest New Mexico. In that comparison, Euphilotes ellisii has moderately checkered wing fringes; males have a compact pink/orange aurora at the back of the dorsal hindwing; and females have a more compact orange band on the back of the dorsal hindwing. Range and Habitat. This Colorado Plateau insect occurs in arid northwest New Mexico shrublands (counties: MK,SJ,Sv,SF?), usually 5500 to 7200’. Life History. Larvae appear to be restricted to stands of buckwheat brush (Eriogonum corymbosum), so field identification of this plant is key to identifying this butterfly. Flight. Adults fly their one annual air show in late summer. Our records are clustered between August 6 and September 7. Comments. Some authors treat this butterfly as a subspecies of Euphilotes centralis, others as a subspecies of Euphilotes battoides. Pelham (2021) treats it as a full species, in which case we have subspecies Euphilotes ellisii anasazi J. Scott 1998. We follow that approach.
Euphilotes spaldingi (W. Barnes & McDunnough 1917) Spalding’s Blue (updated May 19, 2022)
Description. Spalding’s Blue is the most distinctive member of this genus in New Mexico, with marginal orange spots on ventral forewings and hindwings on males and females, whereas congeners have orange only on the hindwing. Spalding’s Blue also resembles Melissa Blue (Plebejus melissa), but it lacks iridescent blue scintillae in the ventral hindwing submargin and male Melissa’s have no orange above. Range and Habitat. This butterfly occurs in our northern uplands as far south as the Gallo and Manzano Mountains (counties: Be,Ca,Ci,Co,MK,RA,Sv,SJ,SM,SF,Ta,To). It occupies Upper Sonoran to Transition Zone savannas, grasslands and dry meadows with extensive stands of the host, generally 5000 to 9000′ elevation. Life History. Redroot buckwheat (Eriogonum racemosum; Polygonaceae) is the only known host, even at its southeast limit in Manzano Mountains State Park and at its easternmost occurrence at Eagle Nest Lake State Park. Eggs hatch immediately so larvae can feed and pupate before winter. Flight. Euphilotes spaldingi is univoltine with adults on the wing in summer. Our records fall between June 27 and August 25. While flying about host racemes in grassy savannas, adults seek nectar at flowers and siphon nutrients from mud created by summer rains. Comments. This species was once considered a subspecies of Euphilotes rita. Our populations belong to subspecies Euphilotes spaldingi pinjuna J. Scott 1981, in recognition of the pinon/juniper savanna habitat it often occupies. The first New Mexico record dates to 6 August 1907 from near Ft. Wingate (MK), probably collected by John Woodgate and now in the American Museum of Natural History in New York.
Euphilotes stanfordorum Opler and A. Warren 2009 Stanfords’ Blue (updated June 1, 2023)
Description. On Stanfords’ Blues, the ventral hindwing orange band tends to be less continuous. Male uppersides look rather like Rita Blue, with an orange halo and prominent black dots along the hindwing submargin. Field identifications depend on larval host identification and are best if confirmed by microscopic examination of the blues’ ‘naughty bits.’ Range and Habitat. This species occurs in limited populations from southwest Colorado and southeast Utah into extreme northwest New Mexico. The first New Mexico record belongs to Irwin Leeuw, who in 1997 snatched a couple of mid-May specimens northeast of Aztec (county: SJ), where mesas at 5500-6000’ elevation support the obligatory larval host. Life History. Larvae eat only cushion buckwheat (Eriogonum ovalifolium), a low-growing plant that sprouts spherical, white inflorescences in spring. Larvae eat succulent spring growth, then pupate. Chrysalids overwinter and adults emerge the following spring. It is likely that pupal diapause can be extended for multiple years. Flight. Across its range, adults fly from late April into late May, never wandering far from stands of the host. In New Mexico this seems to be the only spring flying Euphilotes. Comment 1. When caught, this butterfly was first thought to be a form of Euphilotes ancilla, then later of Euphilotes enoptes, also spring flyers. In 2009, it was described as its own distinct species by Opler and Warren. Comment 2. The specific epithet honors long-time, hard-working, well-deserving Colorado lepidopterist Ray Stanford and his wife Kit, who took the senior author under their wings during his early years in New Mexico. Thanks, Ray and Kit! Comment 3. This butterfly’s known range could expanded by tracking down additional Eriogonum ovalifolium stands in northwest NM. Comment 4. On 21-vii-1997 Kilian Roever captured a Euphilotes species in SJ just below the Colorado border (3 mi NNW of Cedar Hill) associated with Eriogonum ovalifolium, with the notation “this needs study.” It certainly does; the species was reported as Euphilotes battoides, but the locality and host association points to stanfordorum (undescribed at the time). However, the date is late for stanfordorum. Comment 5. We have a number of records for Euphilotes ancilla (probably barnesi Opler & M. Fisher, 2009) which are likely centralis. However, there are more SJ county records for early June which are probably stanfordorum, from the vicinity of Aztec. The host plant for ancilla is Eriogonum umbellatum, a plant which is very rare in northern New Mexico.
Euphilotes rita (W. Barnes & McDunnough 1916) Rita’s Blue (updated May 21, 2022)
Description. Rita’s Blue follows the general Euphilotes look, but minor differences are apparent. The topside orange band on female hindwings is rather broad. On males, the dorsal hindwing pink/orange aurora is more fully expressed and is accompanied by four or five well-defined, circular black spots in the submargin. The dorsal forewing black margin is thin, no more than 10% of the wing radius, as in Ellis’ Blue but not Central Blue. Fringe checkering is weak. Ventral forewing black spots are prominent, less smeared. Range and Habitat. Rita Blues lives throughout the American Southwest and northern Mexico. In New Mexico, they occupy Upper Sonoran Zone grasslands and shrublands where the larval host prospers (counties: Ca,DA,Gr,Hi,Lu,MK,RA,Sv,SJ,SF,Si,So), typically 4800-8000’ elevation. Life History. Larvae eat various Eriogonum species available in their habitat around the state (see below). As with congeners, pupae overwinter. Flight. Adults perch upon and nectar at August- and September-blooming stands of their small perennial woody shrub hosts. Adults never wander far, but they often go to moist soil. Euphilotes rita flies relatively late in the season. Comment 1. At elevations from 4800 to 7,000 feet, southwest and south-central New Mexico have subspecies Euphilotes rita rita (counties: Ca,DA,Gr,Hi,Lu,Si), whose larvae eat Eriogonum wrightii var. wrightii. Records for this form span July 15 to October 16. Comment 2. The southern Rocky Mountains subspecies, Euphilotes rita coloradensis (Mattoni ), inhabits shrublands and savannas of our north-central mountains and foothills (counties: MK,RA,Sv,SJ,SF,So), 5500 to 8000’ elevation. Larvae of eat Eriogonum effusum, E. rotundifolium, perhaps E. lonchophyllum and others. A population of Rita Blue at Sevilleta National Wildlife Refuge in central New Mexico (So) (see photo below) is hosted by Eriogonum effusum, so it is placed here. Our records span August 6 to September 9.
Euphilotes pallescens (Tilden & Downey 1955) Pallid Blue (updated May 22, 2022)
Description. Pallid Blue is paler than other buckwheat blues in three ways: the ventral ground color tends toward white as opposed to gray, the VHW black spots are small, and the VHW orange band tends to be thin. Range and Habitat. Look for this blue in the Colorado Plateau shrublands of UT, NV, northern AZ, western CO, and northwest NM (counties: MK,SJ). Life History. This species is said to be associated with a small number of different buckwheats, as described below. Flight. Adults fly from mid-August to mid-September. They roost, perch, court, mate and nectar among the host plants. We have very few New Mexico records and therefore our knowledge is rudimentary. Comments. Colorado Plateau ssp. Euphilotes pallescens emmeli (Shields 1975) has lighter blue males and uses Eriogonum leptocladon in NW NM (SJ). A largely sympatric race uses Eriogonum microthecum (MK). Much remains to be learned about this butterfly in New Mexico.
Glaucopsyche piasus (Boisduval 1852) Arrowhead Blue (updated May 24, 2022)
Description. Arrowhead Blue has bright blue males and blue-brown females. The hindwing below has a diagnostic band of white, arrowhead-shaped spots. The forewing below has a prominent postmedian band of white-ringed black spots. Range and Habitat. Glaucopsyche piasus lives in montane western US, inhabiting mixed woodlands. In New Mexico it has a limited distribution in mountain ranges ringing the San Juan Basin (counties: Ci,MK,Sv,SJ). It is found from 7,000 to 9,000′ elevation in the Zuni, Chuska and Mt. Taylor ranges. Life History. Females place eggs on various lupines (Lupinus spp.; Fabaceae). Ferris and Brown (1980) and Scott (1992) exclusively cite Lupinus argenteus (Silver Lupine) which is common in northern New Mexico and the probable host for our populations. Chrysalids overwinter. Flight. Arrowhead Blues have one annual brood. Adults are out and about from May 2 to June 30, peaking in late May and early June. Adults bask and perch on host lupines, but will travel to gather nectar and sip electrolytes from moist earth. Comments. We have subspecies Glaucopsyche piasus daunia (W. H. Edwards 1871).
Glaucopsyche lygdamus (E. Doubleday 1841) Silvery Blue (updated July 16, 2022)
Description. Glaucopsyche lygdamus is unmarked glossy blue on the upperside, one of our more beautiful blues. Prominent postmedian bands of white-ringed black spots decorate the undersides against a pale, grey-tan background. Range and Habitat. Silvery Blues live in much of boreal North America from northern Alaska south to Baja California, east to Newfoundland, and south to the Ozarks and Appalachians. In New Mexico it occupies upland savannas and meadows (counties: Be,Ca,Ci,Co,Gr,Ha,Li,LA,MK,Mo,Ot,RA,Sv,SJ,SM,SF,Si,So,Ta,To, Un), generally 6500 – 11,000’. Life History. Larvae eat legumes (Fabaceae) such as Lupinus argenteus, Oxytropis lamberti, Thermopsis divaricarpa and Astragalus spp. Lupinus sierrae–blancae is used in the Sacramento Mountains (Li,Ot). Pupae overwinter. Flight. Silvery Blues are broadly univoltine in New Mexico with adults in flight from March 22 to July 27, depending on elevation; one very late record is August 28. Peak flight varies from May in the Gila and Sacramento Mountains to June farther north. Adults feed at flowers and moist soil. Comments. New Mexico has four named subspecies of which the two best known are Rocky Mountain subspecies Glaucopsyche lygdamus oro (Scudder 1876) in north-central New Mexico and Mogollon Rim subspecies Glaucopsyche lygdamus arizonensis McDunnough 1936 in southwest New Mexico mountains. Richard Holland (2011) described Sacramento Mountains and Sierra Blanca (Li,Ot) subspecies Glaucopsyche lygdamus ruidoso (R. Holland 2011). He also described the race from the volcanic uplands of the Raton Mesa complex (Co,Un) as Glaucopsyche lygdamus erico (R. Holland 2011).
Celastrina echo (W. H. Edwards 1864) Echo Azure (updated September 9, 2022)
Description. This lovely species is sky blue above; females have a wide gray/black border on the dorsal forewing. Undersides are grizzled, frosty white with darker gray marginal dots, submarginal chevrons and postmedian dots or dashes. Echo Azure is considerably larger than the similarly-marked and aptly named Tiny Blue (Zizula cyna). Range and Habitat. A butterfly of the western US, Echo Azure lives in Upper Sonoran to Canadian Zone canyons and deciduous woodlands in most New Mexico mountains (all counties but Ch,Cu,DB,Gu,Ha,Qu,Ro), between 4000 and 10,000′ elevation. Life History. Larvae eat shrubs, vines, or small trees in many families. Examples include Jamesia americana (Saxifragaceae), Prunus virginiana (Rosaceae), Ceanothus fendleri (Rhamnaceae), Humulus lupulus (Moraceae), Calliandra eriophylla (Fabaceae) and Lupinus argenteus (Fabaceae). Flight. Echo Azures complete up to three generations per year in the long growing season of southern New Mexico; records fall between January 22 and December 1, peaking in May. In northern New Mexico, Echos are double-brooded. The greatest numbers are usually seen in spring, from late April into mid-June, with a reduced summer flight in July and August. Comment 1. Celastrina echo is the western North American counterpart to the eastern Spring Azure, Celastrina ladon Cramer 1780. Comment 2. North-central New Mexico montane populations (counties: Co,LA,Mo,RA,Sv,SF,SM,Ta) have boldly marked undersides and can be placed with Rocky Mountain subspecies Celastrina echo sidara (Clench 1944). S. Cary witnessed oviposition on Holodiscus dumosus (Rosaceae) in the Sangre de Cristo Mountains (SF). Form marginata turns up occasionally in the Jemez and Sangre de Cristo Mountains. Comment 3. Populations in central and southern New Mexico (counties: Be,Ca,Ci,DA,Ed,Gr,Hi,Li,Le?,Lu,MK,Ot,Si,So,To,Va) have ventral maculations that are subdued gray and therefore seem to belong with southwest subspecies Celastrina echo cinerea (W. H. Edwards 1883). Comment 4. Celastrina taxa are in a state of flux; not so long-ago lepidopterists recognized only one species – Celastrina argiolus (Linnaeus, 1758) – in the US. That species was thought to be distributed across the northern hemisphere. Recently, argiolus has been limited to the Palearctic and North American populations have been divided into at least 9 species. It is possible that in New Mexico, more than one species will eventually be uncovered. The Mexican Azure (Celastrina gozora [Boisduval 1870]) has been reported from New Mexico, but here we consider those specimens to be cinerea. A form of the Lucia Azure (Celastrina lucia lumarco J. Scott 2006) was described from Delta County, CO and may be one of those to be added to our list. The Hops Azure (Celastrina humulus J. Scott & D. Wright 1998) was also described from CO; NM specimens associated with hops (Humulus) should be closely examined to see if any are Hops Azures. Finally, the recently-described eastern US species seem to be associated with particular larval host plants and NM Celastrina may be found to have such “host races” as well.
Tailed-Blues. The two species of Tailed-blues in North America are currently assigned to the genus Cupido Schrank and subgenus Everes Hübner. Eastern (Cupido comyntas) and Western Tailed-blues (Cupido amyntula) look alike. Phenotypic characters exhibit sufficient variability within each species, and overlap between the two species, such that photographs alone may not be determinable to species. Ferris and Brown (1981) indicated that microscopic examination of genitalia may be the only sure way to tell one from the other. More recently, Glassberg (2017) echoed that there is no sure way to separate Eastern and Western in the field. Those challenges are irrelevant in vast areas where only one or the other exists. In the American Southwest, however, we are fortunate to have both and so we make our best effort to determine which is which. Key characters to look for include: (1) width of the black margin on dorsal forewings of males; (2) extent of basal blue scaling on dorsum of females; (3) development of orange spots/lunules, dorsal and ventral, near the hindwing tail; (4) orientation of line connecting two uppermost black postmedian spots (Bailowitz & Brock 2022); and (5) straight vs. rounded forewing apex and edge. (6) Higher elevation sites above 8000′ elevation generally produce Westerns while Easterns seem largely limited to sites below 6000′.
Cupido comyntas (Godart ) Eastern Tailed-blue (updated June 21, 2022)
Description. Eastern Tailed-blues usually have well-developed orange spots or lunules near the HW tail, on males and females, dorsally and ventrally. Dorsally, male Eastern Tailed-blue is blue with a broader (>2mm) black margin on the forewing compared to Western. Females are gray-brown with blue over-scaling covering the inner half of the wings, with more blue in spring than in subsequent broods. Range and Habitat. Eastern Tailed-Blue is a meadow and field denizen in the eastern US. Colonies also occur farther west in the Sierra Nevada, northern Mexico, and from southern Arizona to west Texas. In New Mexico (counties: Ca,DA,Ed,Gr,Hi) it likes moist areas below 6000′. Life History. Legumes (Fabaceae) are hosts for larvae; clovers (Trifolium spp.) may be preferred. Specific New Mexico hosts have not yet been elucidated. Flight. Cupido comyntas completes two or more broods annually in southwest New Mexico. In Animas Valley cienegas (Hi), adults fly continuously between March 5 and October 24. Adults fly near the ground, gather nectar and sip moisture. Comments. Knowledge of this species in New Mexico may be masked by its similarity to the more widespread Western Tailed-blue. Recent reports from northern New Mexico (counties: MK,Ci,Ta,SM) challenge traditional views of Eastern Tailed-blue in New Mexico. They may represent misidentifications or, if correctly identified, may have originated as accidental introductions in alfalfa hay imported from other states.
Cupido amyntula (Boisduval 1852) Western Tailed-Blue (updated June 30, 2022)
Description. Cupido amyntula males are bright blue above with a narrow (~1mm) black margin. Males have hindwing tails and associated black dots with a range of orange caps or lunules: no orange lunules, one small orange lunule, or one full plus one small orange lunule. Females are dark grey above with basal blue overscaling of variable extent and some orange near the tail. Underside tail toppers for both sexes usually include two orange hats, one full and one reduced. Cupido amyntula usually has a straighter FW outer edge than Cupido comyntas. Range and Habitat. Western Tailed-Blues live from Alaska to the Great Lakes, south to California, Arizona and New Mexico, where they occupy montane woodlands and savannas (counties: Be,Ca,Ci,Co,Gr,Hi,Li,LA,Lu,MK,Mo,Ot,RA,Sv,SJ,SM,SF,Si,So,Ta,To,Un), 6500’to 9000′. Life History. Larvae eat legumes (Fabaceae) such as Astragalus flexuosus, Lathyrus spp., and Vicia americana. Larvae overwinter. Flight. Cupido amyntula is univoltine in north-central New Mexico, peaking in June. It completes two generations in our southern mountains, spanning April 19 to September 30, peaking in May and August. Comments. New Mexico Western Tailed-blues fall on the phenotypic spectrum between northern Rocky Mountain subspecies C. a. albrighti (Clench 1944) and southeastern Arizona subspecies C. a. herrii (F. Grinnell 1901). Aberration jemezensis Gunder was described from Jemez Springs (Sv) in 1927. Given the uncertainty of identifications of this species and C. comyntas, we have included all reports of C. amyntula on our map, with the caveat that some of these records are tentative. The only way to firmly establish the distribution limits or boundaries of this species and C. comyntas in New Mexico will be to examine genitalia from specimens from many localities in the state. Meanwhile, the elevation criterion is expected to work for field identification in more than 90 per cent of situations.
Hemiargus ceraunus (Fabricius 1793) Ceraunus Blue (updated July 5, 2022)
Description. Ceraunus is gray or tan below with slightly darker bands on the forewing beneath, but lacking the prominent row of dark spots sported by Reakirt’s Blue. The hindwing underside has dark ocelli near the tornus, with white and light brown marks elsewhere. Above, males are iridescent light blue, while females are brown with basal blue iridescence. Range and Habitat. This tropical butterfly breeds along Atlantic and Pacific coasts of Mexico and Central America, then north as far as south Florida. Vagrants and strays regularly invade the southwestern US, including New Mexico (counties: Be,Ca,Ch,Cu,DB,DA,Ed,Gr,Gu,Ha,Hi,Li,LA,Lu,MK,Ot,Sv,SM,SF,Si,So,To,Va). It establishes seasonal breeding colonies in southern New Mexico, but they do not survive our winters. Less common and less widespread than the similar Reakirt’s Blue, which is a breeding resident statewide, Ceraunus is reported most often from under 7,000′ elevation. Life History. Larvae feed on a variety of legumes (Fabaceae), such as Medicago, Cassia, Lotus and Prosopis. Seasonal reproduction is likely in southern New Mexico. Flight. Ceraunus adults are recorded from May 13 to October 31, peaking in July to September. They go to nectar and moist earth. Comments. Our populations are subspecies Hemiargus ceraunus gyas (W. H. Edwards 1871).
Echinargus isola (Reakirt) Reakirt’s Blue (updated July 10, 2022)
Description. Reakirt’s looks like Ceraunus, but the forewing underside has a prominent band of white-ringed, dark spots. If these blues were larger, this difference would be obvious, but their small size dictates that observers take a close look to get a correct identification. Range and Habitat. A variety of habitats in Mexico, Central America and the southwest US are core breeding areas for this butterfly. It has been one of our most common and widespread butterflies (all counties), 3000 to 10,800′ elevation. Life History. Many legumes are hosts, including species of Melilotus, Medicago, Mimosa, Astragalus, Acacia, Prosopis, and Trifolium. Larvae eat flowers and fruits and are attended by ants. Flight. As one might expect from a common species with many hostplant choices, E. isola is multivoltine and common much of the warm season. In New Mexico it has been found between January 1 and December 30, so basically year-round, though mid-winter observations are scarce. Adults fly near the ground to find nectar, dung and moist earth. Comments. Reakirt’s Blue has been a known part of our fauna since at least 1880, but it may be more widespread now due to anthropogenic proliferation of weedy and agricultural legumes. It occasionally strays far to the north and east of New Mexico (Michigan, Minnesota, Ohio, etc.).
Icaricia lupini (Boisduval 1869) Lupine Blue (updated July 8, 2022)
Description. Iridescent green-blue spangles accent ventral hindwing submarginal orange bands of Lupine blues. These scintillae distinguish Lupine blues from all Buckwheat Blues, which lack them. Melissa Blues have scintillated orange bands on ventral forewing and hindwing. On uppersides, Lupine males are blue, while females are dark grey/brown with various degrees of blue overscaling; both sexes have dorsal hindwing orange bands with black centers. Range and Habitat. Lupine lives from southwest Canada across the western US to Mexico, from coast to the high Plains. In New Mexico (all counties) Lupine is widespread from deserts to treeline. Life History. Ironically and perhaps humorously, larvae of Icaricia lupini apparently do not eat lupines; they eat wild buckwheats (Polygonaceae) such as Eriogonum corymbosum, E. annuum (RA), E. cernuum and E. wrightii (Ca). S. J. Cary witnessed an oviposition on E. jamesii var. wootonii on 1 July 2000 (Li) and that observation is now presumed to have involved a female Lupine Blue. Lupine Blue larvae may also feed on some Fabaceae; we won’t know for sure until species limits in this group have been firmly established. Adults feed at nectar, dung and wet sand. Flight. Lupine Blue is multivoltine; adults have been found all months of the year as far north as Albuquerque (Be). High altitude observations may be of a related species, Icaricia cotundra (J. Scott & M. Fisher 2006). Comments. We may have subspecies Icaricia lupini texanus Goodpasture 1973, at least in southwest NM. Northern counties may have Icaricia lupini lutzi (dos Passos 1938). Lupine Blue is a member of a complex of very similar species. Challenges with this multi-species group reveal the inadequacy of photographs when genitalic examination or DNA analysis is ultimately required to distinguish one from the other. There are multiple reports of Icaricia acmon (Westwood ) from New Mexico; that species is now thought to be mainly a Pacific Coast beast, but who knows? Mother Nature does not always fit her creatures into convenient boxes for us humans. For now, all New Mexico reports of I. acmon are treated here as I. lupini.
Icaricia (Plebejus) saepiolus (Boisduval 1852) Greenish Blue (updated July 15, 2022)
Description. Greenish Blue males are glossy blue above with a cell-end black bar. Females are iridescent blue-brown. Below, they are tan or grey with a postmedian row of white-rimmed black spots, a submarginal row of double spots (this is diagnostic), and a definite hint of orange at the ventral hindwing tornus. Range and Habitat. Boreal Canada and the Rocky Mountains harbor this species. It occupies the higher mountains in New Mexico (counties: Ca,Co,LA,Mo,RA,Sv,SJ,SM,SF,Ta), generally 7500 to 12,500′. Life History. Larvae eat legumes (Fabaceae) such as Trifolium spp. (clovers) and Astragalus spp. Larvae overwinter. Flight. Adults fly in one mid-summer generation. New Mexico records fall between May 28 and September 2, with peak numbers in July; there is an odd October 3 record. Adults fly near the ground, nectar at clovers and sip at wet sand. Comments. We have Rocky Mountain Icaricia saepiolus whitmeri (F. Brown 1951), whose females are brown above. The Mogollon Rim (Ca) has the smaller I. s. gertschi dos Passos 1938, whose females are blue above. The species is (apparently) curiously absent from the higher mountains in central New Mexico.
Icaricia icarioides (Boisduval 1852) Boisduval’s Blue (updated July 15, 2022)
Description. Boisduval’s is our largest blue, but still not very big. Males are iridescent sky blue above with black edging. Females are dark gray above with blue basal scaling. Beneath, the forewing has a bold postmedian band of white-ringed black spots and a similar cell-end bar. The hindwing underside is gray with small, dark submarginal chevrons and a postmedian band of white-ringed black spots. There is a gap between submarginal chevrons and postmedian band. Range and Habitat. Icaricia icarioides lives throughout the western US, occupying habitats from sea level to Hudsonian Zones. New Mexico populations prefer Transition and Canadian Zone montane savannas and meadows (counties: Ca,Ci,Co,Gr,Li,LA,MK,Mo,Ot,RA,Sv,SJ,SM,SF,Si,Ta,Un) with stands of the host plant, generally 7500 to 12,500′. Life History. Larvae of Boisduval’s Blue eat various Lupinus spp. (Fabaceae). Of the many lupine species in New Mexico, Lupinus argenteus is favored in the north. Mike Toliver saw oviposition on this lupine at Capulin Mountain (Un), 20 June 1971. It also is the primary host on Burnt Mesa in Bandelier National Monument (LA). Other lupines probably are acceptable as well. Part-grown larvae hibernate. Flight. Icaricia icarioides is univoltine here. New Mexico records fall between May 6 and August 20, with peak numbers in June and July. Adults seek nectar (e.g., Amorpha canescens, Eriogonum racemosum) and wet soil, and are happy to perch on lupines. Comments. Great geographic variation in this species has resulted in proliferation of named subspecies by taxonomists (25, by our last count). Most New Mexico populations are grouped with central Rocky Mountains race Icaricia icarioides lycea (W. H. Edwards 1864), which has bold ventral hindwing black cell spots. Colonies on the Mogollon Rim and nearby areas (Ca,Gr,Si) belong to ssp. I. i. buchholzi dos Passos 1938, whose males have a wide black border on the upperside. Populations in the Raton Mesa Complex (Co,Un) can have females that are dorsally black and are subspecies I. i. nigrafem (R. Holland 2011). Populations in the Sierra Blanca complex (Li,Ot) colonize the endemic Lupinus sierrae-blancae and are subspecies I. i. sacre (R. Holland 2011), though this was not recognized by Pelham (2021).
Agriades glandon (de Prunner 1798) Arctic or High Mountain Blue (updated July 20, 2022)
Description. Male High Mountain Blues are variably shimmering silver-blue above with dark margins, black cell-end bars and black hindwing marginal spots. Females are brown. High Mountain Blues’ gray-tan underside has forewing black spots and distinctive hindwing white spots. The female ventral hindwing margin has hints of orange. High Mountain Blues resemble Boisduval’s but the hindwing underside has a postmedian spot band that is pushed out toward the submarginal spot band. Range and Habitat. Agriades glandon or its kin occur across arctic and subarctic regions of the northern hemisphere. It occupies most of Canada and extends southward in cold Rocky Mountain habitats as far as New Mexico (counties: Be,Ca,Ci,Co,LA,MK,Mo,RA,Sv,SJ,SM,SF,So,Ta,To), 8000 to 12,500′. Life History. Hosts in the Rocky Mountains are Primulaceae such as rock jasmines Androsace septentrionalis and A. chamaejasme. Flight. Agriades glandon is univoltine with adults in flight during summer. New Mexico records fall between May 11 and October 3, clustering in June and July. Adults fly near the ground, perching, basking, nectaring and puddling. Comments. Some workers consider Agriades to be a subgenus within the genus Plebejus. North-central New Mexico populations are Agriades glandon rustica (W. H. Edwards 1865). Those in the south-central to southwestern mountains (Ca,So) are tentatively placed with Agriades glandon punctatus Austin 1998.
Plebejus melissa (W. H. Edwards 1873) Melissa Blue (updated July 3, 2022)
Description. Male Melissas are bright iridescent blue above; females are brown with orange submarginal bands. Below, both sexes are gray-white with dark marks; submarginal bands of orange spots are capped by black dots packed with iridescent blue scintillae. This distinguishes them from the similar Spalding’s Blue (Euphilotes spaldingi). Range and Habitat. Melissa Blues occur from western North America east to New England in varied habitats. In New Mexico it prefers disturbed areas, agricultural margins and riparian corridors (all counties but Cu,Hi,Le,Lu), 3300 to 10,000′. Life History. Host legumes (Fabaceae) in New Mexico are often Astragalus spp., but Lupinus, Vicia, Medicago, Lotus and Hedysarum also are used. Larvae ate blooms of Oxytropis sericea near Capulin Mountain (Un), 27 May 1972 (Mike Toliver). Adults perched on Glycyrrhiza lepidota at the Pecos River (Ch), 3 August 1997 (S. Cary). Ova overwinter. Flight. Plebejus melissa is bivoltine in southern New Mexico and at low elevations; records span March 29 to December 1, with peaks in May to June and September to October. Upward and northward it is univoltine, with maximum numbers in from June to August. Adults seek nectar and water. Comments. Our populations belong to the nominate subspecies.