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More butterfly magnets

2010 August 12

PHOTO BY KEN MOORE. Silver spotted skipper is one of several butterflies attracted to swamp milkweed.

By Ken Moore
Flora Columnist

Four weeks ago (Flora, 7/8), I featured swamp milkweed, Asclepias incarnata, because of the pair of milkweed leaf beetles that hung around for weeks and weeks. My milkweeds have completed flowering for this year, and those two beetles, who did finally get together, are now gone.

On a recent visit to the N.C. Botanical Garden, I was delighted to find dozens of swamp milkweeds in pots still flowering in the sales area. Adding to the beauty of those pink flowers were the numerous butterflies flitting about and feeding on flower nectar. I had not remembered butterflies much attracted to the single milkweed in my garden.

The spectacle at the Botanical Garden demonstrated that having several of these milkweeds in proximity somehow creates an irresistible attraction for butterflies, as well as other pollinators. I plan to have several plants grouped together growing in my garden next year. I visited the garden again this past weekend and those flowers are still attracting butterflies.

Another wildflower that is a magnet for various species of butterflies is ironweed, Vernonia novaboracensis. Like swamp milkweed, it’s another tall wildflower common along streams and in wet meadows. Ironweed is easily cultivated and surprisingly tolerant of drought. I planted one in a flower border a few years back and now, from self-seeding, I have several new plants growing nearby. They have grown tall during our recent dry spells and now multiple clusters of brilliant purple flower heads attract numerous swallowtails and skippers.

It’s great fun to sit in the late afternoon near those purple-topped stems with binoculars in hand to focus on the butterflies as they flit about and alight on those flower heads. A beautiful contrast is the rusty-colored hue, hence the name ironweed, of the seed heads that begin forming soon after pollinators have performed their function.

Of course, you don’t need binoculars to take a closer look at the butterflies and other pollinators on the heads of the ironweed. Those insects are so engaged in extracting nectar from the flower tubes that you can practically touch them. And with a keen eye, you can zoom in on the details of those clusters of disc flowers. You may even notice the split, curled tips of the stigmas of the pistil (female part of the flower) extending from each flower tube.

Using a 10-powered hand lens is always a big help when you take this kind of closer look.

Though both swamp milkweed and ironweed are fairly common in moist habitats throughout the state, they are surprisingly seldom noticed unless you are driving on back roads in the mountains, where in low meadows you’ll spot the brilliant purple-flowered ironweed contrasting with the yellow of goldenrods and the tall pinkish domes of Joe-Pye weed. In our vicinity, keep your eyes alert along edges of roadside drainage ways and open meadows. You’ll most likely have to rely on seeing them in gardens, or, better yet, grow your own.

Email Ken Moore at flora@carrborocitizen.com.

Eastern tiger swallowtail taking nectar from ironweed heads of tubular disc flowers.

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