The Wood Folk Diaries: Volume 3, Chapter 3: Paper Birch and Canadian Tiger Swallowtails and Trembling Aspen, Oh My

Dear Wood Folk,

I’ve seen and taken pictures of dozens of tiger swallowtails around Haliburton, and every single one of them was identified as a Canadian tiger swallowtail (papilio canadensis). Eastern tiger swallowtails don’t seem to get north of Oshawa much, and hybrids (p. canadensis × glaucus) are rare. There’s also a rare black female form.

From mid-May to late July they are a frequent sight here! Here’s a salt-craving couple mud-puddling or sun basking:

Canadian tiger swallowtail (papilio canadensis) mud-puddling
Canadian tiger swallowtail (papilio canadensis)

Attracting Canadian Tiger Swallowtails

Paper birch and trembling aspen trees are the two most popular host plants for Canadian tiger swallowtails. They sometimes use ash, apple, cherry, willow and other birch, cottonwoods and poplar trees. Shrubby alder and mountain ash may also host the larvae. The pupae overwinter here.

Attracting them is easy, even a dandi will do for this guy:

Canadian tiger swallowtail (papilio canadensis)
Canadian tiger swallowtail (papilio canadensis)

The old lilac hedges on dirt roads in my area are covered with swallowtail when in bloom. The founding bushes around here typically mark where the first homesteaders on the lot had their outhouse. There’s a hedge immediately across the road from the one I frequent and I don’t know if it’s an escapee or if a neighbour later planted some suckers from the original. Lilac isn’t a native plant but it’s not super aggressive and all sorts of bees and butterflies seem to flock to it during its brief blooming time. Swallowtails are especially known for their taste for it. Lilac bloom time is also when I’m luckiest for spotting hummingbird moths.

The Lilac Debate

The light purple common lilac (syringa vulgaris) is unfortunately considered an invasive species here. It doesn’t spread fast or aggressively but it can escape into the wild.

And while the bees and butterflies are attracted to lilac like it’s magnetism, native plants like chokecherry get even more traffic and pack more value overall. Alternate leaved dogwood, any kind of cherry thicket, red elderberry, serviceberries, etc., will get tons of pollinator traffic and have similar looks and niche to lilac.

Recommendations vary out there even from native plant enthusiasts. Doug Tallamy, whose presentations (you can find on YouTube! Here’s a recent one.) have led many a gardener to invest in native plants, suggests 70% native and 30% your choice (though obviously not super invasive or banned plants!) There are sterile cultivars to consider for those who want to scratch the lilac itch. They tend to be pink or dark purple.

More flowering possibilities to consider: blue flag iris, coneflowers, cup plant, goldenrod, and Joe-pye weed are some of the native plants these butterflies enjoy the nectar of. “Early goldenrod” is a great choice for them – it’s always great to plant multiple native goldenrods for a longer season for this powerhouse native. Swallowtails aren’t picky eaters and aren’t likely to starve, but since native plants tend to be more suited for native insects it’s a smart idea to make sure the healthiest food choices abound for them!

If you have space for their two favoured native host trees, both paper birch and quaking aspen have a white bark that makes a nice contrast on a woods edge. (I have a thing about finding paper birch on the end of woods or a meadow, it pops!)

Having some sunny, mineral rich spots of bare dirt and rocks will attract them too, and perhaps keep them off the dirt roads where they sometimes get ran over while mud-puddling or sun basking.

Next month we’ll met Springs first butterflies. Have you ever seen a butterfly, when there is still snow on the ground, and thought it was lost?

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