Plants and Animals
Callophrys irus Frosted elfin
Key Characteristics
Wingspan 0.8-1.2 inches (2-3 cm). Short tails present. Both sexes are dark brown. Hindwings have short, taillike projections. The undersurface of the forewing has an irregular postmedial line; the outer half of the hindwing is lighter than the base and dusted with purplish scales. A distinct black spot is located near the tail. The caterpillar is yellowish green with white lines and dashes and is covered with brownish hairs.
Status and Rank
US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G3 - Vulnerable
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable
Occurrences
| County | Number of Occurrences | Year Last Observed |
|---|---|---|
| Allegan | 24 | 2021 |
| Bay | 1 | 1964 |
| Iosco | 1 | 2012 |
| Kalamazoo | 1 | 1987 |
| Kent | 1 | 2003 |
| Lake | 2 | 1989 |
| Mecosta | 1 | 1990 |
| Monroe | 1 | 1975 |
| Montcalm | 5 | 1992 |
| Muskegon | 4 | 2021 |
| Newaygo | 6 | 2021 |
| Oceana | 5 | 1997 |
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Habitat
Along roads, trails, forest openings where larval hosts grow. Oak savannas, open areas, and forest edges in proximity to lupine. The larvae feed upon the fruits of lupines (Lupinus sp.) and false indigos (Baptisia spp.). Adults have been seen nectaring on blueberry.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Management Recommendations
Frosted elfin subpopulations on sites with extensive lupine are more likely to persist than those on sites with less lupine. Shading from tree canopy and competition from sod-forming grasses and sedges have excluded lupine from many former barrens and prairies where it once was common. Consequently, disturbances that reduce tree and shrub canopy cover are necessary for lupine to persist, and under some conditions, occasional disturbances that remove the litter layer are needed for lupine regeneration. Disturbances that may be beneficial for renewing lupine habitat, include prescribed fire, tree removal, and a variety of methods to kill trees and shrubs. Well-planned fire management is an important tool for rehabilitating and eventually maintaining Karner blue habitat. The frequency of fire management should be tailored to each management unit, taking into consideration the desired final community matrix, current community conditions, site characteristics, and the life histories of all fire sensitive species present. On a large scale, the final product should be a landscape complex of barrens, prairies and woodlands at different stages in succession. In this setting, semi-isolated Frosted elfin populations within the landscape complex would wax and wane as lupine populations changed, and would provide colonizers to sites recently opened by fire or to sites where butterflies have been lost to localized extinction events. Poorly timed or poorly located use of herbicides can have a negative effect on Frosted elfin butterflies by killing or suppressing lupine or important nectar plants. Mowing between late spring and midsummer is anticipated to have detrimental effects on Frosted elfin populations.
Active Period
Flight from fourth week of April to first week of June
Survey Methods
Larvae are present from June until pupation in the fall. Eggs are laid among developing flower heads and the larvae feed on lupine seed heads. In Michigan, adults of this species have been documented from late April to late May. These butterflies are easily overlooked; adults fly close to the ground, alighting on dead leaves and twigs.
Visual, aerial net
Survey Period: From fourth week of April to first week of June
Time of Day: Daytime
References
Survey References
- Klots, A.B. 1951. Peterson Field Guides: Eastern Butterflies. Houghton Mifflin Company, Boston. 349pp.
- Martin, J.E.H. 1977. The Insects and Arachnids of Canada (Part 1): Collecting, preparing, and preserving insects, mites, and spiders. Publication 1643. Biosystematics Research Institute, Ottawa.
Technical References
- Bouseman, J.K. and J.G. Sternburg. 2001. Field Guide to Butterflies of Illinois. Illinois Natural History Survey, Champaign. 264pp.
- Evers, D.C. 1994. Endangered and Threatened Wildlife of Michigan. The University of Michigan Press, Ann Arbor. 412pp.
- Glassberg, J. 1999. Butterflies through Binoculars: The East. Oxford University Press, New York. 242pp.
- Klots, A.B. 1951. Peterson Field Guides: Eastern Butterflies. Houghton Mifflin Company, Boston. 349pp.
- Nielsen, M.C. 1999. Michigan butterflies and skippers: A field guide and reference. Michigan State University Extension Bulletin E-2675, East Lansing. 248pp.
- Stehr, F. W. 1997. Michigan Lepidoptera Survey Sites and Seasonal Occurrence of Michigan's Listed Species Annual Report 1997. 30 pp.+ MI Lepidoptera Survey Data Collection Form