Black swallowtail. Submitted photo


Last week I had an email from my friend Carol from Abiquiu asking me to identify a beautiful yellow butterfly…the Tiger swallowtail. I had written an article on swallowtails the year before (it’s in the archives) and mentioned that here in Maine we have been inundated with these gorgeous creatures for more than a month. I was presently seeing them in my garden feasting on peonies and lemon lilies, they are also drawn to an old fashioned moon honeysuckle and my wild roses. Since Monarchs and Swallowtails are my favorite butterflies I am thrilled to be seeing so many in Maine.

Imagine my surprise when a stunning blue – black butterfly landed on my foot as I was sitting on the ground this morning. I recognized the swallowtail instantly even though it has been a number of years here in Maine since I have had a visitation from one of these black morphs belonging to the Tiger swallowtail family.

Her very beautiful dusky grey-black wings and blue spotted tail create some confusion because they appear very similar to the Black swallowtail a close relative. But Black swallowtails are midnight blue black with bright yellow and blue spots along with bright orange tail markings. If you have seen a Tiger swallowtail you will surely recognize either of these butterflies, the black morph or the black swallowtail butterfly as a swallowtail.

These butterflies range from southern Canada to Northern Mexico and can be found throughout the western states. The Tiger and the Black Swallowtail are also common along the eastern seaboard. To date I have seen just one Black swallowtail in Abiquiu, and that was in 2018. I remember the vivid red penstemon that this butterfly seemed so drawn too. The color contrast between the two was astonishing.

All swallowtails like to be near water and are drawn to fields and open areas as long as it’s not too windy. Here in the hollow it is very protected and I notice that I have many kinds of butterflies including the Black swallowtail although they are not as common. Perhaps it is my gardens that the others are attracted to because I have many pollinators and stay away from cultivars that don’t attract insects at all.

Swallowtails feed on members of the carrot family which include Queen Annes lace, celery, dill, parsley. They also gravitate to water hemlock and are also very fond of lilac blossoms. Around here they seem to feast on virtually any flower I have in bloom.

The first generation emerges in the spring after overwintering in a chrysalis. The butterflies mate and then deposit green (tiger) or yellow (black) eggs on the underside of the chosen leaves. Lilacs are a favorite host plant. The eggs hatch in three to five days into gorgeous striped caterpillars who begin munching for about 9 to 11 days before pupating for less than a month before becoming adults. All swallowtail larvae have reversible horn-like organs behind the head known as osmeteria. When threatened, larvae rear up, extrude the osmeterium, and attempt to smear the potential predator with a chemical repellent! The second group of butterflies mates in the late summer and their eggs overwinter in chrysalis form and become the first butterflies to appear in late April to June. Because swallowtails only live about 2 weeks to a month I often find dead ones, and have to remember that these gorgeous butterflies soared through the fragrant spring and summer air during their brief moment in time.

Some insect parasitoids locate their hosts by volatile chemicals in the feces (Vinson 1984). Black swallowtail larvae, like those of some other swallowtail species, throw their fecal pellets with the mandibles (Lederhouse 1990).

Black swallowtail caterpillars utilize a variety of herbs in the carrot family (Apiaceae) as host plants, including:

Native species:

Mock bishopweed, Ptilimnium capillaceum (Michx.) Raf.

  • Roughfruit scaleseed, Spermolepis divaricata (Walter) Raf.
  • Spotted water hemlock, Cicuta maculata L.
  • Water cowbane, Oxypolis filiformis (Walter) Britton
  • Wedgeleaf eryngo, Eryngium cuneifolium (Small)

Introduced species:

  • Poison hemlock, Conium maculatum L.
  • Queen Anne’s lace, Daucus carota L.
  • Wild parsnip, Pastinaca sativa L.

They will also eat a variety of cultivated herb Apiaceae, including:

  • Caraway, Carum carvi L.
  • Celery, Apium graveolens L. var. dulce (Mill.) DC.
  • Dill, Anethum graveolens L.
  • Parsley, Petroselinum crispum (Mill.) Nyman ex A.W. Hill
  • Sweet fennel, Foeniculum vulgare Mill.

They will also use common rue, Ruta graveolens L., in the citrus family (Rutaceae).

All plant parts of both spotted water hemlock and poison hemlock and some other wild species are extremely poisonous if eaten and may also cause contact dermatitis. Care should be exercised when handling these plants and they should never be planted as caterpillar hosts. A potion of poison hemlock was used in ancient Greece to execute prisoners and is believed to be the poison taken by Socrates. Black swallowtail caterpillars are able to detoxify the furanocoumarin chemicals (particularly the linear forms) in these and other toxic Apiaceae (Berenbaum 1981).

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