FROSTED ELFIN (Callophrys Irus Irus)
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FROSTED ELFIN (Callophrys irus irus) The frosted elfin (Callophrys irus irus) is a small gossamer-wing butterfly found in remnant oak-pine barrens. As far as elfins go, it is a larger specimen with a wingspan between 0.8-1.4 inches. It is active in late spring and early summer and is non- migratory. Its larvae are specialists and require indigo or lupine for food. Adults can be observed nectaring on spring shrubs and berries. Their patterning is subtle and cryptic. The upper-sides are a uniform dark grey-brown. The Frosted elfin butterfly, credit: Will Cook undersides are a lighter orange- brown and has more grey in its coloring. Edges of the wings are frosted with light gray scales bordered by an irregular dark line. The lower third of the hindwing is also frosty gray with an identifying dark spot near the series of short tails. Males and females are similar, except that males will also have a dark stigma on the forewing and will behave more territorially than females. The larvae (caterpillars) are pale greenish-white with a pale lateral line and oblique dashes along the sides and covered in short whitish hairs. Frosted elfin caterpillar, credit: Will Cook At one time the frosted elfin was found surrounding the Great Lakes and along the east coast from New Hampshire to Florida and west to Texas (USFWS 2018). Habitat alteration, including loss of specific food plants and places to live and grow during critical life stages has, over the past 30 years, reduced the species’ range and abundance. Frosted elfin now occur primarily in local colonies of remnant habitats along the eastern coast, Great Lakes, and Texas/Louisiana borders. This species is considered critically imperiled in Maryland (NatureServe 2019) with historic records scattered throughout the State. The U.S. Fish and Wildlife Service (Service) is proactively assessing the conservation status of the frosted elfin to determine whether or not the species may warrant Federal protection under the Endangered Species Act. The Service has completed Stages 1 and 2 of a Species Status Assessment (SSA) (USFWS 2018). An assessment of the species viability in light of ongoing conservation efforts (Stage 3) will occur prior to making a listing determination (USFWS 2018). Through the SSA process, it was evident that data concerning species distribution and habitat were greatly lacking so additional surveys were conducted at locations with more recent observations. Survey results will be used to further refine priority restoration areas. LIFE HISTORY The entire lifecycle of a frosted elfin is completed within 1 year. This non-migratory butterfly has one flight from late April through mid-June (Williams et al. 2014; NYNHP 2019). Eggs are laid singly on a leaflet, flower bud, or bud stalk of the hostplant (WDNR 2015). In Maryland, the phenology is such that frosted elfin eggs can be found on all parts of wild lupine, but only on indigo leaflets. Eggs are reported to hatch in 1 week (Albanese et al. 2008). Caterpillars progress through four instars while feeding on both flowers and developing seedpods (wild lupine) or the leaves and stems (indigo) of host plants. Larvae pupate by late July in the north east (Albanese et al. 2008), and remain in pupal diapause until the following spring. Hibernation occurs on or near hostplants in leaf litter or beneath the soil surface (Opler and Krizek 1984; NYNHP 2019; Selfridge et al. 2019). HABITAT Frosted elfin butterflies require open woods, forest edges, and scrub in which their larval hostplants grow (Wagner et al. 2003). Historic habitats included pine barrens, oak savannas, and dry oak forests. Although females lay eggs on hostplants throughout the habitat, hostplants with some canopy shade have higher larval survival (Albanese et al. 2008). In Wisconsin, the majority of occupied habitats observed (97 percent) ranged from 2 to 79 acres (Swengel 1996). Frosted elfin density has also been correlated with higher density of indigo plants (Albanese et al. 2007). Dispersal distances greater than 2 km are considered unlikely across areas without hostplants (NatureServe 2019). As frosted elfin habitats are lost, this butterfly has become increasingly restricted to areas with frequent anthropogenic disturbances such as utility rights-of-way, railroad corridors, recreational trails, and airport buffers (Shepherd 2005), becoming a remnant-dependent species. While fire as a management approach for frosted elfin is debated, it remains an important tool for supporting lupine communities (Pavlovic and Grundel 2009). In the north east, rotational burn programs have been used with great success in both frosted elfin and karner blue habitats (Bried et al. 2012). However, in Wisconsin, frosted elfin were found less often than expected in areas that received rotational burns versus areas disturbed by natural fires (Swengel 1996). Therefore, the decision to use fire as a management tool should be made on a site basis and fire programs should always use an over-abundance of caution. LARVAL HOSTPLANTS The primary hostplants of frosted elfin are yellow wild indigo (Baptisia tinctoria) and wild lupine (Lupinus perennis), which thrive in dry woodland habitats with frequent fires (USFWS 2018). Frosted elfin adults will occasionally use blue wild indigo (B. australis). There appears to be a preference for wild lupine in the Maryland populations, but there is insufficient data to confirm these observations (pers. communication, J. Selfridge). Males are territorial, so multiple patches of hostplants are needed to accommodate several territories (Swengel 1996). Larvae were more likely to be found on large (greater than 6.5 square feet) areas of indigo plants (Albanese et al. 2008). 2 ADULT NECTAR PLANTS Adult frosted elfin are nectarivores. An adult frosted elfin is a flower generalist, primarily requiring only successional blooming from early spring through mid-summer for nectaring. As adults are almost always found within 50 feet of one of the larval hostplants (NYNHP 2019), nectar supply is needed in the same habitat. Frosted elfins have been observed feeding on a variety of flowers including wild lupine and bird-foot violet (Viola pedata) (Swengel 1996), blueberry (Vaccinium spp.), huckleberry (Gaylussacia spp.) (Thom 2013), pin cherry (Prunus pensylvanica), sweetbells (Leucothoe racemosa), and staggerbush (Lyonia mariana) (Schweitzer et al. 2011) and Rubus spp. (Allen 1997). Adult frosted elfin are also reported to feed on moist sand (Swengel 1996), likely a source for salts and minerals. HABITAT RESTORATION RECOMMENDATIONS Priority Areas in Maryland (Figure 1) Eastern Shore: Dry open wooded areas in Worcester and Wicomico Counties in and around Snow Hill and Dorchester County near Federalsburg. Western Maryland: Dry open wooded areas in Garrett County, particularly near utility corridors. Pay close attention to sites with a mining history. Expansion: Caroline County has both Figure 1. Maryland conservation priorities by county. Counties wild lupine and yellow wild indigo, is outside of historic frosted elfin range are lowest priority adjacent to known populations of frosted elfin, and part of its historic range. Habitat Quality Description and Target Plant Species Frosted elfin rely on disturbance-dependent dry open pine-oak woods. Remnant habitats often involve scrub and forest edges, which need to be carefully maintained as canopy cover can be an issue for this species and its hostplants. Prime frosted elfin habitat will maintain a hostplant density of at least 2.6 plants/m2 and canopy cover is less than 29 percent (Albanese et al. 2007). High quality frosted elfin habitat will have high hostplant and native herbaceous cover and maintain and open habitat by limiting tree and shrub coverage. • Larval hostplants – limiting factor for reproduction o Yellow wild indigo (B. tinctoria) . Hostplant of frosted elfin in MD . Common throughout MD o Wild lupine (L. perennis) . Suspected preferred hostplant of frosted elfin in MD . Considered imperiled (NatureServe 2020) and protected as State-threatened under Maryland Department of Natural Resources (MD DNR) . Known to be used by frosted elfin in NY, PA, DE, MA, and VA 3 . Historically throughout the State, though sometimes in small populations. Used by frosted elfin in Worcester County o Blue wild indigo (B. australis) . Rare observances as hostplant of frosted elfin in MD . Considered imperiled (NatureServe 2020) and protected as State-threatened under MD DNR . Occurs in Washington, Montgomery and Prince George’s Counties. No overlap with known frosted elfin populations • Adult nectar sources o Bloom period from early April to early July; flower generalists o Includes early blooming native trees and shrubs COMMON NAME SPECIES RANGE IN MD Forbs Blue wild indigo Baptisia australis See larval hostplants Yellow wild indigo Baptisia tinctoria See larval hostplants Wild lupine Lupinus perennis See larval hostplants Wild bergamot Monarda fistulosa throughout Smooth penstemon Penstemon digitalis throughout Violets (blue/purple) Viola spp. throughout Shrubs New Jersey tea Ceanothus americanus Central MD and Dorchester county Black huckleberry Gaylussacia baccata throughout Carolina rose Rosa carolina throughout Berry canes Rubus spp throughout Lowbush blueberry1 Vaccinium angustifolium Western MD and counties surrounding D.C. Hillside blueberry1 Vaccinium pallidum throughout Trees Eastern redbud Cercis canadensis throughout Pin cherry Prunus pensylvanica Western MD and scattered counties 1 observations indicate that Vaccinium