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Montana Field Guides

Subarctic Bluet - Coenagrion interrogatum

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Species of Concern
Native Species

Global Rank: G5
State Rank: S1S2
(see State Rank Reason below)

Agency Status

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State Rank Reason (see State Rank above)
This damselfly is currently listed as an "S1S2" Species of Concern in MT due to extremely limited and/or rapidly declining population numbers, range and/or habitat, making it highly vulnerable to extirpation in the state. This restricted range may be due to lack of suitable surveys to detect this dragonfly. With more surveys this species will likely be found in more areas across the western portion of the state. The Subarctic Bluet appears to be very habitat specific to the marshy lakes of northwest MT, limited collecting contributes to it's vulnerable state status as well.
General Description
The Subarctic Bluet is much less common than the Taiga Bluet and is very localized rather than widespread. This small bluet inhabits cool beaver ponds or peat bogs. It can be found in a limited area of Northwest MT in late spring and summer. The small damselfly is 30 mm long (~1 in.). The male is black and bright blue. It can be distinguished from the Taiga Bluet by the broken shoulder stripe and the abdominal banding. In this Bluet, the blue color of the stubby hindmost segments extends into the preceding long segment, unlike the all black long segment of the Taiga Bluet. Females may be blue or greenish with narrow light bands on the abdomen. Like all bluets, the Subarctic Bluet is a weak flier and rests horizontally with wings folded over the abdomen.

Diagnostic Characteristics
It can be distinguished from the Taiga Bluet by the broken shoulder stripe and the abdominal banding. In this bluet, the blue color of the stubby hindmost segments extends into the preceding long segment, unlike the all black long segment of the Taiga Bluet.

Species Range
Montana Range Range Descriptions


Range Comments
This species is found throughout Canada and in several of the northern and northeastern states, including most of New England (Paulson 2009). Currently the Subarctic Bluet is only known from Spencer and Howe Lakes in Flathead County (Miller and Gustafson 1996).

Observations in Montana Natural Heritage Program Database
Number of Observations: 5

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

This species is not known to migrate.

The preferred habitat for Subarctic Bluets is open boreal fens and bogs, as well as marshes and beaver ponds with abundant mosses and sedges (Westfall and May 1996, Acorn 2004, Paulson 2009).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Larvae feed on a wide variety of aquatic insects, such as mosquito larvae, other aquatic fly larvae, mayfly larvae, and freshwater shrimp. Adult damselfly will eat almost any soft-bodied flying insect including mosquitoes, flies, small moths, mayflies, and flying ants or termites.

Reproductive Characteristics
Male Subarctic Bluets tend to be more present in dense vegetation and not in open water. Copulation usually occurs while perched on nearby upland shrubs. Oviposition occurs in tandem or by single females on floating grass and sedge leaves as well as grass stems (Paulson 2009).

Threats or Limiting Factors
Drought and associated water-level changes are considered the greatest immediate threats to known populations. Although this species is widespread and common in much of Canada, it is rare and sparsely distributed at the southern edge of its range (NatureServe 2011), and climate-related changes in habitat suitability may threaten populations and shift the species’ distribution northward.

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Citation for data on this website:
Subarctic Bluet — Coenagrion interrogatum.  Montana Field Guide.  .  Retrieved on , from