Nannothemis Brauer, 1868
Nannothemis bella (Uhler,1857) - Elfin Skimmer
Fig. 1: Nannothemis bella larva (3x, dorsal view), from a roadside ditch atJuniper Creek,
Calhoun Co., Florida, collected on 18 March 1974 by M. J. Westfall,Jr.
Specimen loan courtesy of B. Mauffrey, IORINotes -References
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Page last updated: 04 April1999 (EB)
Notes onNannothemisbella in Michigan
Our smallest Anisopteran, mature larvae do notexceed 11 mm in length. (Maturity is recognized when the wing sheathsreach abdominal segment 6).
Larval habitat appears to be small pools andpuddles away from the water's edge in the sphagnum of fens and bogs.Walker and Corbet(1975) report this species being commonin floating sphagnum bogs, where females oviposit in warm temporarywater 2-5 cm deep. Although numerous adults specimens from Michiganare in various institutional collections (Kielb 1997), few larval specimens exist undoubtedly due to poorcollecting effort and difficulty of finding this species' evidentlyspecific microhabitat. Recently (04 April 1999), I (EB) havecollected in Washtenaw County, southeastern Michigan, nearly maturelarval specimens in a habitat resembling that described by Walker andCorbet. A floating mat composed of Carex sp. andSphagnumsp., with leatherleaf around the edges, resides in the middle of anlarge pond in an interlobate morainal regions. The pond is fairlyshallow, with Nuphar sp. and reeds growing throughout much of the area, andcattails and red-osier around the pond edges. This seepage pondappears to have a thick bottom layer of organic material - the waterappears to have high gilven, the pH was 6.8, the conductivity about50 uS cm-1, and little alkalinity (23 mg/l CaCO3, phenopthalein-acidtitration). On the sphagnum mat, however, water-filled depressionshad a pH of 5.1, conductivity of 30 uS cm-1, and an alkalinity ofonly about 1-2 mg/l CaCO3. These "holes" are indeed tiny, and onesuch depression about 25 cm wide, 1 m long and 30 cm deep yielded 8larvae, both mature and one considerably less-developed specimen(two-year life cycle, or two different populations?). N. bella appear common inthese holes, but are very difficult to find. Apart from their verysmall size, distrubed larvae "freeze," which makes them difficult tofind among the sphagnum debris, even when submerged in water. Somelive larvae put in a container filled with sphagnum slowly burrowedinto the debris, their bodies, being densely covered with attachedparticulate matter, soon became rather cryptic.
Emergence is probably from early to late-June,earlier in southern Michigan, later further north. (However, 1998 hasbeen a very early year, and I (EB) collected an adult in the thirdweek of May in Lenawee County). This species is widely dispersed inour state (Map 1, below).
Map 1: County distribution ofNannothemisbella in Michigan
Click on map for a larger image
Other links with information on the biology orecology of larval Nannothemis:
none found as of 20 June 1998
Brauer, F. M. 1868. Verzeichnis der bis jetzt bekanntenNeuropteren im Sinne Linne's. Verh.Zool.-Bot. Ges. Wien 18:359-416,711-742.
Kielb, M. A. 1997.Nannothemis bella (Uhler) in Michigan (Libellulidae). Williamsonia1(2):4.
Uhler, P. R. 1857.Contributions to the Neuropterology of the United States.Proceedings of the Academy of NaturalSciences of Philadelphia1857:87-88.
Walker, E. M. and J.S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. 3. Universityof Toronto Press: Toronto. xvi + 308.