Center for Ecological Research

Frosted Elfin (Callophrys irus) Breeding Ecology in Eastern Massachusetts

Adult Frosted Elfin photographed in eastern Massachusetts, by Gene Albanese

Frosted Elfin habitat use in open sandplain communities

The distribution of Frosted Elfin, a small early successional butterfly, once extended from the southern Canada, northeastern United States, south to Florida and west to Texas and Wisconsin. Although its global range is large, frosted elfin is non-migratory, and occurs in relatively small, localized populations.   Populations have declined severely in the last 50 years, and are now limited to remnant habitat patches and anthropogenic habitats previously occupied by native sand barrens and savanna. It is probably extinct from Canada and has the greatest number of state listings of any non-federally listed butterfly species in the United States (Nature Serve 2003). In Massachusetts, it is considered both uncommon and a Species of Special Concern. However, the population within the state is one of the species’ last strongholds.

Forsted elfin populations depend on early successional plant communities containing wild indigo (Baptisia tinctoria) and/or wild lupine (Lupinus perennis) (Opler and Miliikul 1992, Scott 1986, Schweitzer 1992).  These plant communities are found in xeric-open habitats maintained by natural and anthropogenic disturbances on sandy substrates (Wagner et al. 2003, Swengel 1998, Panzer et al. 1995, Panzer 1984).  Wild indigo and wild lupine are signature plants of early seral sandplain communities within Massachusetts, and their persistence is dependent on frequent disturbance (Swain and Kearsley 2001).

Frosted elfin is a univoltine species that over winters as a pupae.  Adults emerge in Massachusetts from mid-April to mid-May.  The flight period is approximately six weeks starting in late April and lasting through mid-June with the peak flight usually occurring in mid-May.  Females lay single eggs on the host plant, and the larvae develop and remain on the plant for a six week period, pupating by late July.

Frosted Elfin larvae in eastern Massachusetts feed exclusively on this plant species, Wild Indigo (Baptisia tinctoria). Photo by Gene Albanese

Implications of canopy cover on a rare barrens butterfly, the frosted Elfin (Callophrys irus).

The frosted elfin is a localized and declining butterfly found in xeric open habitats maintained by disturbance. Because accurate identification of a butterfly’s habitat must include the requirements of all life stages, we examined woody plant canopy cover, topography and host plant size and density, and used these features to describe the microhabitat of host plants containing late instar frosted elfin larvae.  We also assessed whether females preferentially oviposited eggs on host plants within specific microhabitats, therefore conferring greater survivorship through larval development to the late instar stage.  In southeastern Massachusetts, United States, we surveyed four study sites for adults. We searched this species’ sole host plant, wild indigo (Baptisia tinctoria), for late instar larvae, and measured seven vegetative and environmental features at plants containing larvae.  We then compared these observations to plants on which we observed adult females depositing an egg and also to random plants containing no evidence of late instar larvae.  We found that moderate amounts of canopy cover and large plant size characterized larvae occupied host plants.  In the absence of tree canopy cover, late instar larvae density remained low even when host plant density was high.  These results indicate that canopy cover was an important characteristic of microhabitats containing late instar larvae and late instar larvae occupancy was determined by suitable microhabitat conditions and not female oviposition selection.  We recommend managing for canopy cover and microhabitat heterogeneity within open habitats to maintain frosted elfin populations.

Larval feeding behavior and ant association in Frosted elfin

 Frosted Elfin is a rare and declining lycaenid butterfly found in the eastern U.S., inhabiting xeric and open habitats maintained by disturbance. Populations are localized and monophagous. During a larger research assessment of the multi-scale habitat requirements of Frosted Elfin, we documented a previously undescribed larval feeding behavior, and observed frequent association of larvae with several species of ants. Observations both in the field and of captive-reared stock revealed girdling of the main stem of the host plant by late-instar larvae. Girdled stems provide a unique and universal feeding sign that was useful in detecting the presence of larvae in the field. We provide a list of ant species observed associating with larvae, and suggest two hypotheses on the potential benefits of stem-girdling to Frosted Elfin larvae. Photo by Gene Albanese

References

Albanese, G., P. D. Vickery, and P. R. Seivert. 2007.  Habitat characteristics of adult frosted elfins (Callophrys irus) in sandplain communities of southeastern Massachusetts, USA.  Biological Conservation, in press.