|scientific name Calopteryx aequabilis |
common name River Jewelwing
Small to moderate forest streams (Walker).
Present from early June to early September, infrequent earlier (Walker).
The only all-metallic green damselfly with coloured wings in Alberta. The wings are smoky to black in the distal half, with many antenodal cross veins. Quite large (>45mm). Males: wings black in distal half, brownish yellow in remainder, no pterostigma. Females: wings smoky brown in the distal half, brownish yellow in remainder, white pterostigma.
Mating occurs shortly after emergence (males are only prereproductive for 5 days on average). Males often display to females by hovering over a potential oviposition site and diving into the water, laying the wings flat on the water's surface. Only flying females are displayed to. Oviposition is conducted by the unaccompanied female well below the surface of the water. Eggs are laid in submerged aquatic vegetation (Corbet). Nymphs develop over 2 to 3 years (Walker). Adults have been known to congregate, and will flock to avoid perceived threat (Corbet).
The species has not been known in Alberta for long. It seems somewhat uncommon, but its status is uncertain.
Gleans small invertebrates from the foliage. The nymphs prey on aquatic invertebrates.
Restricted to northeastern Alberta (Clifford). Found east to Nova Scotia and P.E.I., and has recently been found in southern B.C (field note, RBC Museum). It is also found in much of the U.S.A., especially the northeast.
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