Plants and Animals
Dichagyris reliqua The relic
This small noctuid moth has a wingspan of 2.3 to 2.6 cm and is recognized by the contrasting white hindwings and dark-tan forewings (Schweitzer et al. 2011). The caterpillar feeds on the ripening seeds of prairie dropseed (Sporobolus heterolepis), and the adult moth doesn’t fly far away from its host plant (LaFontaine 2004). In New Jersey, the larvae are known to mature in September then burrow into the soil where they overwinter without pupating. Some individuals remain in diapause for at least two winters, possibly longer (Schweitzer et al. 2011).
Status and Rank
US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G2 - Imperiled
State Rank: SNR - Not ranked
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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.
Caterpillars feed on prairie dropseed (Sporobolus heterolepis), and may be associated with other lepidopterans (e.g., Hesperia leonardus and H. ottoe) that share the same host plant.
This species may be one of the rarest insects in eastern North America and is primarily endemic to the Niagaran Escarpment around the Great Lakes in the United States and Canada, comprising many disjunct populations (LaFontaine 2004). Most occurrences of this species are on high- quality bluff prairies along the Niagara Escarpment and Driftless region of Wisconsin, Minnesota, and Manitoba. Disjunct populations occur in the pine barrens of New Jersey, NW Florida, and NE Wyoming (LaFontaine 2004). The approximately 15 occurrences in the Midwest are found primarily in prairie remnants. Within Michigan the species thus far has only been recorded in alvar, but could possibly occur in other natural communities.
Specific Habitat Needs
Host plant needed in: Alvar.
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.
Surveys and monitoring to assess the status and extent of this species’ distribution in Michigan are needed including searching in other communities that contain the host plant. Given the rarity of this moth, remnant populations should be protected and carefully managed. It is likely that habitat destruction and the use of herbicides and pesticides negatively impact this species. Where this species occurs in alvar habitat, off-road-vehicle traffic should be prohibited. Across its range, much of the prairie habitat of this moth has been destroyed for agricultural. In prairie remnants, use of prescribed fire is recommended. Fire likely stimulates seed production by this species host plant prairie dropseed. Intense fires in spring through early summer may also provide the larvae cues to break diapause (Schweitzer et al. 2011).
Flight from fourth week of July to fourth week of August
The best way to survey for this species is by blacklighting, a technique where a sheet is stretched across two trees or poles and an ultraviolet light is used to attract moths to the sheet. Moths can be collected directly from the sheet. Insects come to light usually in largest numbers on still, dark, cloudy nights when both temperature and humidity are high. This species is difficult to identify in the wild. It is strongly recommended that observations of this species be verified through actual specimen vouchers or verification by a species expert.
Survey Period: From fourth week of July to fourth week of August
Time of Day: Night
Cloud Cover: Overcast
Air Temperature: Above 60 degrees
Wind: No Wind
Survey Method Comment: Here we present ideal conditions, however surveys can be conducted during other conditions as well.
- Covell, Charles. A Field Guide to the Moths of Eastern North America. Peterson Field Guide Series, Houghton Mifflin Company, Boston, MA. 496 pp.
- 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.
- Bess, J. 2009. A Report on Surveys for the Karner Blue Butterfly and Other Rare Insects at Whitewater Wildlife Management Area: With an Assessment of Habitat Quality and Recommendations for Management and Monitoring. February 16, 2009.
- Lafontaine, J.D. 2004. Noctuoidea: Noctuinae. The Moths of America North of Mexico, Fascicle 27.1. 385pp.
- Pohl, G.R. J.-F. Landry, B.C. Schmidt, J.D. Lafontaine, J.T. Troubridge, A.D. Macaulay, E.van Nieukerken, J.R. deWaard, J.J. Dombroskie, J. Klymko, V. Nazari, and K. Stead. 2018. Annotated checklist of the moths and butterflies (Lepidoptera) of Canada and Alaska. Pensoft Publishers. 580pp.
- Schweitzer, D. F., M.C. Minno, and D.L. Wagner. 2011. Rare, Declining, and Poorly Known Butterflies and Moths (Lepidoptera) of Forests and Woodlands in the Eastern United States. U.S. Forest Service, Forest Health Technology Enterprise Team, FHTET-2011-01. USDA Forest Service, Morgantown, West Virginia. 517pp.