The Swallowtail Butterflies Leave the Madman
It’s mid-July and the baby swallowtails have left the nursery plant. Seems they left all at once. At one time, we would have been concerned and blamed the birds – after all, our friend the Black-capped Chickadee (Poecile atricapillus) has been known to eat them. But, now, we know it’s just Mother Nature taking her course – they have wandered off to pupate.
What are we talking about? A beautiful native caterpillar, often referred to as the Parsley worm (Papilio polyxenes). You might know it as the Black Swallowtail Butterfly. We have been raising them for years, but, in truth, we did it by accident.
The Accidental Host
Years ago, I purchased a Bronze Fennel (Foeniculum vulgare ‘Purpureum’) plant because I liked the color of the feathery leaves. The madman was still in his “Don’t grow it if you can’t eat it” stage, so I told him how it would pair well with fish, pork and poultry. I even said the seeds are good in sausage. That seemed to quiet him down. Over the years, the fennel has thrived, almost to the state of escaping control – I have fennel everywhere.
Over 100 Species
Although sources differ on the number of butterfly and moth species native to Connecticut, we can safely say there are over 100 such natives. As the madman says, nature doesn’t really adhere to man-made boundaries, so on any given day, there may be more, or there may be less. Butterflies are drawn to a particular area by the availability of food supplies, water, other butterflies and a place to lay eggs. The Parsley worm the madman had found was on what is known as a host plant.
Host plants are the preferred places for female butterflies to lay eggs. As the eggs hatch, the host plant will nourish the growing caterpillar. It’s interesting how different butterflies like different plants for egg-laying. The Connecticut Audubon Society has a good list of host plants for the common Connecticut butterflies.
Black Swallowtail Butterflies
Black Swallowtail butterflies prefer plants in the Apaceae family. You know, parsley (Petroselinum crispum) – that’s why it’s called the Parsley worm. Other family members are dill (Anethum graveolens), fennel (Foeniculum vulgare), carrot (Daucus carota subsp. Sativus) and Queen Anne’s lace (Daucus carota). In late spring, a female Swallowtail butterfly lays more than 200 eggs over the course of several days. The eggs are deposited singly on leaves of host plants. The eggs begin to hatch in 10-14 days. Over the course of the next 3-4 weeks, the caterpillar will eat its way through five stages, called Instars. The madman often says that the best description of this process comes from a book written by his favorite children’s author, Eric Carle, called The Very Hungry Caterpillar.
Wanderers
When the caterpillar is ready to pupate, it wanders as far away from its host plant as it can get. That’s why we don’t see them anymore. The next time we do see them, they will be beautiful fliers looking for nectar to drink and host plants to lay the next generation of eggs on.
And, that’s why host plants alone are not enough. In a true butterfly garden, you need host plants, nectar plants, and a source of water, shelter and a place to rest. It seems that the butterflies are less fussy about nectar plants than they are about host plants. They will go to just about any flower, but milkweeds, lantanas, zinnias and coneflowers seem to be sure bets. Single-flowered varieties as opposed to double are best because they produce more nectar and offer a nice landing site for the butterflies. The madman recommends you add a comfy chair from which to watch the activity.
The Black Swallowtail butterfly isn’t the only species of Swallowtail we find in our garden. We are also visited by the Spicebush Swallowtail (Papilio Troilus), Eastern Tiger Swallowtail (Papilio glaucus) and, if we are lucky in late summer, the elusive Giant Swallowtail (Papilio cresphontes). You would think that each of these species would be happy with the fennel, but, no, each species prefers a different host plant for egg-laying.
Spicebush Swallowtail Butterflies
As its name suggests, Spicebush Swallowtail butterflies lay eggs on Spicebush (Lindera ssp.) or Sassafras (Sassafras albidum). The first thing this caterpillar does when it hatches is eat its eggshell. It will then use silk it produces to curl a leaf where it will stay when not eating. The adult butterflies look very similar to the Black Swallowtails, and honestly, when they are flying around, we can’t always tell the difference.
Eastern Tiger Swallowtail Butterflies
But, we can tell the Eastern Tiger Swallowtail butterfly male because it is yellow (sometimes the females are black just to confuse us). This species uses trees as host plants, preferring Ash (Fraxinus ssp.), Birch (Betula ssp.) and Willow (Salix ssp.) in our yard. Like the Spicebush Swallowtail, the caterpillar eats its eggshell and produces silk to curl a leaf for a hide-out when not eating.
Giant Swallowtail
Giant Swallowtail caterpillar at rest. 
Giant Swallowtail caterpillar when disturbed.
The last species we see is the Giant Swallowtail, the largest of all North American butterflies. This is the madman’s favorite, not only for its size and color (brown with yellow markings), but for its fascinating caterpillar – perhaps the ugliest thing I have ever seen. This guy looks like a bird dropping, but produces ferocious looking horns when disturbed. Actually all Swallowtail species produce these horns, called osmeteria, which are used as a defense mechanism.
Host plants for the Giant Swallowtail include citrus (Citrus ssp.) and Hercules’ Club (Zanthoxylum clava-herculis), a plant that doesn’t grow in Connecticut. In citrus groves, this caterpillar is considered a pest, although the madman is happy to have them on his citrus plants. He considers the damage they cause incidental and a small price to pay for watching the caterpillars.
Getting Ready for Visitors
At this point, we have no more caterpillars to check on, and in all honesty, we don’t know where they have gone to pupate. The madman figures we have about two weeks before they emerge from chrysalis stage and we see the next generation of butterflies. He’s making sure our garden is ready to feed the new butterflies and host the next generation of caterpillars.
But now, it is time for lemonade.
