Fall 2005
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Fall 2005 |
Attract Dragonflies to Your Yard If your kids are off to college now and you’re already missing their cannonballing off the deck into the portable swimming pool, you can plan this winter to keep your yard buzzing with activity next summer. Replace the pool with a dragonfly pond and watch Cardinal Meadowhawks diving after mates and our state insect, the Green Darner, basking in the sun. Dragonflies, damselflies
and most other members of the insect order Odonata Under the right conditions, even a small pond will attract some of these aerial acrobats to your backyard wildlife sanctuary. If you enjoy bird watching or butterfly-watching, you'll probably love watching dragonflies and their relatives, damselflies. (Dragonfly bodies tend to be larger, with broader wings, than those of damselflies, whose wings taper at the base.) Among the largest of all insects, dragonflies are reasonably easy to identify by their field marks. Close-focus binoculars will help you get a better look. And like birds, male dragonflies are usually territorial and defend their turf aggressively. (No wonder they were a favorite emblem among seventeenth-century Japanese warriors, who called them "invincible insects.") Dragonflies resemble red-winged blackbirds or flycatchers in the way they claim an elevated perch on a stem of wetland vegetation, then sally out to chase away other males or make a mid-air capture of a mosquito. During certain times of year, you'll also see the most striking and entertaining dragonfly behavior: mating in midair. Watch for two dragonflies in the "wheel" position, which means they're in the process of mating, or for damselflies flying tandem, like a car pulling a trailer (the strategy enables males to guard their mates during egg-laying).
Before digging a pond to attract dragonflies, consider whether you live within a few miles to a stream, pond or wetland with a "source" population. You'll get faster results if you do. Dragonflies are strong flyers, though most individuals stay around their natal pond or stream. But a certain number “float” through the landscape and that often means, if you build it, they will come. The next consideration is size. Twenty feet in diameter is approximately the size recommended by the British Dragonfly Society. (The British have dragonfly clubs the way Americans have birding clubs.) However, you don't necessarily need a large pond to attract dragonflies. Something as small as a wooden half barrel will attract breeding damselflies. Whatever the size, place your pond where it will be protected from wind and will get midday sun. The ideal dragonfly pond should vary in depth, shallow at the edges and at least two feet deep in the center. Deep water offers nymphs a refuge from raccoons and other predators. Varied depths are also important to accommodate a variety of water plants. It's not that the nymphs or adults eat the plants, (dragonflies are voracious carnivores at all life stages), underwater plants provide important habitat for the nymphs, which need places to rest, hunt for food, and hide from predators. And emergent vegetation—sedges, rushes and other plants that stick up above the water's surface—provides perching places for adults. Such vegetation is also critical for dragonflies because the nymphs crawl up it when they emerge, making the transformation from water dweller to their free-flying adult form. And though dragonflies don't rely on specific host plants to nourish their young the way butterflies do, some species do use water plants as nurseries. They insert their eggs into the soft stems. What you plant around the pond is almost as important as what you plant in it. Don't mow the border—let the sedges and rushes grow. Make sure you have some shrubs within a few feet of the water. That will provide more perching sites. A couple more design details: Put a few flat rocks near the pond's edge. Dragonflies like to warm up by basking in the sun. It can take a while for pond plants to get established. While you're waiting for your emergent vegetation to grow above the surface of the water, put a few perching sticks in the middle of your pond. Ordinary bamboo stakes—the kind you use to stake plants—will do the job. If you want breeding populations of dragonflies in your pond, it's probably best not to introduce fish, because they will prey on the nymphs and eggs. See http://wdfw.wa.gov/wlm/backyard/ponds.htm for more information about creating a backyard pond, including ways to ventilate it to minimize attracting mosquitos. And with all that done, set out a bench, grab those binoculars or camera and telephoto lens, and enjoy the show. Adapted from “Attracting Aerial Acrobats to Your Yard” by Cynthia Berger, National Wildlife Apr/May 2002, vol. 40 no. 3, with permission from the National Wildlife Federation. Additional References
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