The Dragonflies
(Insecta: Odonata)
of the Columbia Basin, British Columbia:
Field Surveys, Collections Development and Public Education
Table
of Contents
Return to Family Calopterygidae
Calopteryx Leach
Calopteryx damselflies are the largest in Canada.
Their bodies are metallic green with blue reflections, and the legs
are long and black with long, stiff spines. They fly with a dancing,
butterflylike flight and perform striking courtship displays. C.
aequabilis is the only representative in British Columbia.
Calopteryx aequabilis
Say*
River Jewelwing
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Male
C. aequabilis.
Photo: Dennis Paulson. |
Female
C. aequabilis.
Photo: Dennis Paulson.
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Provincial Status
CDC rank: S1
Red List
Known only from one site in the province: Christina Creek at the outlet
of Christina Lake. Columbia-Kootenay Distribution
The only known location of a C. aequabilis population in
the study area is Christina Creek, approximately 18 km east of Grand
Forks. Because this species requires slow-moving warm streams, it
probably will not be found in many other localities in the region.
Global Distribution
C. aequabilis is a widely distributed northern species across
Canada and the USA. Its range is concentrated in northeastern North
America; western populations are disjunct and scattered. In Washington
State it is found more commonly in the southeastern portion of the
state, primarily in lowlands (Paulson 1999). Faunal element: Transition
(see Appendix 2).
Biological Information
Larvae are found in rivers and larger creeks where they cling to
aquatic plants, roots and woody debris. They take two or three years
to develop, and the females take longer than the males. Calopteryx
species have elaborate, well-studied courtship behaviour. Females
lay eggs in floating mats of vegetation. At the Christina Creek
site the females oviposited in Potamogeton illinoensis, an
aquatic plant uncommon in British Columbia. Oviposition was observed
on 17 August. This is probably near the end of the season as only
three individuals were seen. The known flight period in British
Columbia is from 19 July to 17 August (1999); however, it probably
begins earlier and lasts slightly longer. North American dates are
6 May to 2 September (Westfall and May 1996).
For those naturalists wanting to search for this rare
species, the male has dark brown wingtips with the darkened area
larger on the hindwings. In the female the bases of the wings are
diffuse yellow-brown, the tips are brown and there are white pterostigmata
(spots on the front edge of the wing near the tip).
Management and Protection Considerations
The protection of the riparian zone and the maintenance of a relatively
undisturbed edge along Christina Creek is critical. Samways and
Steytler (1996) provide recommendations for width of the riparian
buffer and heterogeneity of the vegetation for species assemblages.
These assemblages are of different species; however their life requirements
are similar. The River Jewelwing uses the vegetation overhanging
the stream for roosting, and floating mats of vegetation for oviposition;
this streamside vegetation would be at risk with development.
Limiting recreational use and controlling the type
of use are also important. Of particular concern is the use of personal
watercraft (i.e. Jet Ski) along the shallow creek where this species
is found. The wakes from these craft break down the banks (observed
directly in this study) and ultimately will collapse the streamside
vegetation.
The impact of introduced predatory fish, especially
bass, on this rare damselfly is unknown, but is definitely of concern.
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