As expected, I found black swallowtail caterpillars on the golden Alexanders in the garden. So I carefully relocated them to otherwise unoccupied dill plants.
One of them was cranky about it.
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deployed!
Yes, those are the osmeterium mentioned in my September 1 post.
checking out the new home
I’m out hunting for wildflowers so often my poor garden is neglected. This year I let about a dozen or more volunteer dill plants grow wherever they came up. They’re a mess now, some still flowering, most gone to seed and looking weedy. I was pulling them out and cutting them back and generally tidying up when I saw this caterpillar…
…and immediately put down the pruners and went inside to fetch the camera. (That’s a serrano pepper behind the dill, by the way.)
There were several, actually, so I stopped pulling the plants and left the insects where they were – there’s plenty of dill to spare, and these caterpillars will soon pupate to later emerge as black swallowtail butterflies.
Black swallowtail (Papilio polyxenes) caterpillars feed on plants in the Apiaceae, mostly on garden plants brought by European colonists: dill, parsley, wild carrots, and fennel.
a late flowering dill plant in my garden, August 31
Learning that, I immediately wondered what they ate before the invasion. I wasn’t the only one asking that question, for the answers were right there on the internet. Among other things they love golden Alexanders (Zizia aurea).
golden Alexanders on Billy Goat B trail, April 29
I love golden Alexanders, too, and bought one from a native plant nursery last spring. Darned expensive little thing. It’s coming along quite nicely, but there isn’t enough green to spare to feed a voracious late instar caterpillar. I don’t know what I’ll do if I find one on the plant. Probably pick it off and move it over to the dill. Hopefully that wouldn’t cause the osmeterium to come out.
Bon appetite, mes beautés!
Zizia aurea; Apiaceae
This perennial member of the carrot family stands about two feet tall and grows in a variety of habitats, from moist to drier open woodlands and in rocky areas, and provides nectar for a large variety of insects that don’t have many other sources in the springtime. It ranges from Quebec to Florida and west into the Great Plains.
The complex inflorescence is an umbel of about a dozen umbellets:
Each umbellet consists of about twenty flowers, each with five inward-curving petals.
In case you’re wondering, yes, these botanical terms share a root with the word “umbrella”. It’s from the Latin umbra, meaning shadow. Umbel-shaped flower heads are typical in the Apiaceae.
The genus is named for botantis J. B. Ziz. What I can’t figure out is why this (and several other) species has the common name Alexanders. If anyone knows, please leave a comment.
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