The Green-eyed Skimmers (49 NA spp) are generally
dark, metallic species with green eyes and a constricted waist, and most
are superb aerialists. Larvae are generally dark, robust hairy bottom
sprawlers in cool water bogs. Minnesota reports 16 species in the
genera Epitheca (=Epicordulia+Tetragoneuria,
4 spp), Cordulia (1), Dorocordulia
(1), Neurocordulia (2), and
Somatochlora (9). Seven species in the genera Epitheca,
Dorocordulia, and Somatochlora have been collected at CCNHA.
The most abundant member of this family is
Epitheca
spinigera, which emerges
by the millions from Fish Lake at the end of May. Vast numbers of tenerals
(young individuals) hang from shoreline vegetation as they dry their wings,
and they later fill the sky where they feed on 'aerial plankton'. Still
later in the month at dusk, females by the thousands course low over Fish
Lake where they drape gelatinous egg strings in huge masses on vegetation
breaking the water surface. Small numbers of Epitheca
canis emerge from Cedar Bog Lake in mid May. Dorocordulia
libera is a common inhabitant of Beckman Lake and the smaller
permanent ponds on the Area. It too emerges in late May and early June.
Patrolling males with their emerald green eyes and strongly constricted
waist are conspicuous on these ponds by late June. Four species of Somatochlora
are considerably rarer and appear in late-July and August. Somatochlora
walshii courses low over fields feeding (larval habitat?), S.
williamsoni patrols the edge of Cedar Bog Lake, and S. ensigera
and S. kennedyi are infrequently encountered along Cedar
Creek.
