Tachopteryx thoreyi
Grey petaltail

Key Characteristics

Large, mostly gray dragonfly. Thorax gray with black stripes, and abdomen black with gray blotches. Separated eyes and linear stigman. Eyes dark brown, becoming gray at maturity.

Status and Rank

  • State Status: T
  • State Rank: S1
  • Global Rank: G4


County NameNumber of OccurrencesYear Last Observed
Distribution map for Tachopteryx thoreyi

Updated 5/15/2018. 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.


Lotic - depositional (margins and moss of spring streams; upper edges of hillside seepages in deciduous forests). Found in forest openings, lowland conifer, lowland hardwood, fens, swamps. Requires woody structure in aquatic habitats.

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.


Species is sensitive to continued decrease in water quality. Also affected by impoundments, channelization, dredging, siltation, non-point pollution (agricultural), and industrial pollution. Timber harvests may increase sitation and cause a decrease in dissolved oxygen. Also affected by altered hydrologic regimes, riparian modifications and wetland modifications. Forest cover and hydrological patterns should be maintained at intact sites and restored at disturbed locations.

Survey Methods

An exuvia survey consists of searching the banks and protruding rocks of rapid streams for the cast skin of dragonfly larvae. It characteristically perches on the trunks of trees and often on people wearing neutral colored clothing. Males can be seen flying up and down the trunks of trees as they meticulously search for females. They rarely stray far from their forest habitat.

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed Sep 23, 2018]


Survey References

Technical References

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