Friday, June 11, 2010
I’m stuck in a flycatcher rut. Last week’s topic was a feathered flycatcher, the Eastern Phoebe. This week I have a different kind of flycatcher, the Ebony Jewelwing. It feeds on all kinds of small insects including gnats and mosquitoes.
Name: The Ebony Jewelwing is Calopteryx maculata where calo is from the Greek ‘kalos’ meaning beautiful and ‘pteryx’ (or pteron) meaning wing. ‘Maculata’ is from the Latin meaning spot and refers to the white spot on the wings of the female. If you have an older insect book you may find it under the name of Agrion maculatum. ‘Ebony’ in the common name refers to the color of the male’s wings.
Family connections: Ebony Jewelwings are members of the insect order Odonata, the group fondly referred to as ‘Odes’ which includes damselflies and dragonflies. The Ebony Jewelwing is a damselfly. Males have a double identity crisis being neither damsels (dudefly doesn’t really work) nor flies but they probably overcome it with pride in their status as ‘broad-winged’. Most of the damselflies we see here are members of the narrow-winged family. They are more delicate and less conspicuous than their broad-winged cousins.
When and where seen: Alan Ankers has recently seen good numbers of Ebony Jewelwings at the Otter Slide trail across the road from the Cranberry Bog, the Blueberry trail in the Greenough land, and Bisbee trail off Concord Street. I have seen them in past years at the North Road canoe launch. They spend time around forested streams and also at sunny spots deeper in the woods where they go to feed. You will be able to see adults up through July and maybe into August.
Identifying characteristics: First, you can separate damselflies from dragonflies by the position of the wings when the insect is at rest. Dragonflies typically hold their wings out at right-angles from their body, while most damselflies hold their wings together above or along their body. Next, dragonflies are much heftier than damselflies. The Ebony Jewelwing male is a strikingly beautiful insect with a slender blue-green metallic body and black wings. It may be as much as two inches long. The females have a dark body and dark gray wings with a white spot near the tip.
Flight: The wing speed of a typical fly is around 1000 beats per second. The wing speed of odes is closer to 30 beats per second. This doesn’t mean they are not good fliers. They can hover, fly backwards, dart, and do vertical take-offs. If you have tried to catch one with a net, you know how evasive they can be. Ebony Jewelwings have a slow fluttering flight pattern more like a butterfly than a darting dragonfly.
Life cycle: Ebony Jewelwings mate in the summer. The female lays her eggs on vegetation at or just below water level. They hatch in about a week into larvae recognizable by the three gills at the tip of the abdomen and the long antennae. They eat small aquatic insects which they reach out and grab with a hydraulic-powered lower lip. They spend the winter in the water and emerge as adults in late spring or early summer of the following year.
Learning more about Odes: There are 166 species of odes known to occur in Massachusetts. I’d like to pass on Alan Anker’s recommendation for a good book to learn about them and help you identify those you find. It is Field Guide to Dragonflies and Damselflies of Massachusetts by Nikula, Loose and Burne and published by Mass Wildlife. While not generally available in bookstores, you can get it at Mass Audubon’s store at Drumlin Farm.
Sources: Insects: Their natural History and Diversity, Stephen A. Marshall; BugGuide.net (an excellent website for insects and ID assistance); A Guide to Observing Insect Lives, Donald W. Stokes (good descriptions of insect behavior – organized by seasons of the year).
Submissions: Please feel free to claim this space and write the Biodiversity Corner about any species that occurs in the wild and can be found in Carlisle. ∆
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