August Nature Almanac: Ebony Jewelwings Dash and Flash Above Languid Streams
By Ruth Carol Cushman and Scott Severs
Photos by Scott Severs
August 2021
Like turquoise and emerald wands with ebony wings, jewelwing damselflies (Calopteryx maculata) make us catch our breath in wonder.
This aptly named broad-winged damselfly likes to perch on low shrubbery along slow-moving, shaded streams, usually facing the water as they watch for prey. When perching, damselflies hold their wings folded over their body, unlike dragonflies who hold their wings horizontal to their body when perched. Useful as well as beautiful, jewelwings eat mosquitos, gnats, crane flies, caddisflies, and other small insects. In turn, jewelwings are eaten by dragonflies, spiders, fish, birds, and frogs.
Damselflies, like this ebony jewelwing, hold their wings folded over their body when perched.
Metallic males put on an elaborate display at this time of year, fluttering their wings and hovering like an animated helicopter in front of a female. The brownish-bronze females are characterized by a white wing cell (pterostigma) on the outer edge of their forewing that may help sexes identify each other. The dance culminates when the female accepts his attentions and he clasps her behind her head with his tail or abdomen forming a heart-shaped loop.
The male has two penises. The primary penis on the tip of the abdomen transfers sperm to a specialized secondary penis that transfers the sperm to the female’s spermatheca (an organ to store sperm) while also brushing out any sperm previously deposited by another male. Copulation lasts from one to six hours. The female then deposits her eggs in the stems of aquatic plants or in plant debris while the male stays nearby to guard her and keep other males away.
Ebony jewelwing in flight.
The eggs hatch into larvae called naiads that undergo several molts before finally molting into two-inch long adults--considered large, as damselflies go! Their lifespan as adults is only 15 to 17 days, but since they are not all born at once, we can continue to enjoy them from late June when they start to hatch here in Boulder until mid to late August. They overwinter underwater as naiads.
Ebony jewelwings are very cooperative photography subjects as they often return to the same perch after sallying out after a bug. If you avoid letting your shadow fall on them, you can usually approach to within a few feet before they fly.
Chiefly an eastern species, ebony jewelwings were rarely seen in Colorado until the past few years. This species probably benefits from protected riparian open spaces free from grazing. Tall trees, shrubs, and grasses that shade slow moving streams may be helping small populations to get established in Colorado. Heavy vegetation also provides preferred overnight roosting areas
The stretch of Coal Creek from Flagg Park to the Public Road Trailhead in Lafayette is one of the best places to see these dazzlers. They become more active as the day warms, and courtship and breeding peak in the afternoon so that’s a good time to look for them. Also watch for American rubyspot damselflies (Hetaerina american), another glittering gem that likes slow moving water.
To reach Flagg Park, take Baseline Road to Flagg Drive (just east of East County Line Road) and turn south. The park is on the left.
Beautiful and deadly, jewelwings are key predators of mosquitos, gnats, crane flies, caddisflies, and other small insects.
Other August Events
Thanks to monsoon rains, mushrooms are popping up in the spruce/fir forest. Look for delectable Boletus edulis and beautiful but poisonous Amanitas sp. under conifers in the montane zone.
Late-nesting goldfinches and Cedar Waxwings are feasting on ripening chokecherries and currants. The brushy area at the bottom of Bear Creek Trail is a good place to find them.
Autumn colors peak on the tundra by the end of the month. Queen’s crown (Rhodiola rhodantha), king’s crown (Rhodiola integrifolia), and big-rooted spring beauty (Claytonia megarhiza) turn crimson while still flaunting pink, rose-red, and white flowers. Alpine avens (Geum rossii) turn russet red, and mountain dryads (Dryas octopetala) turn to gold. Parnassian butterflies continue to nectar on late alpine flowers.
Also on the tundra, pikas (Ochotona princeps) are busy making hay, but yellow-bellied marmots (Marmota flaviventris) are mostly sunbathing. Although marmots used to be seen regularly on the South Mesa Trail and at other locations in Boulder, most of us think of them as a high elevation species. Surprisingly, they have been reported in the Frasier Meadows neighborhood recently.