Wednesday, July 29, 2020

Polydamas Swallotail

The Polydamas Swallowtail, Battus polydamas, is named after both historical and mythological figures from Greek history. Battus I founded the colony of Cyrenaica and its capital Cyrene on the coast of present-day Libya around 630 BC. Impressive ruins are all that is left. 

Polydamas figures in the Illiad as an advisor and friend of Hector. Polydamas of Skotoussa, who won the Olympiad in 408 BC, was an athlete of prodigious strength. Some of his feats appear on Greek pottery. The subspecies that occurs in Florida is Battus polydamas lucayous. I haven't been able to find a reference for "lucayous." 

The polydamas is the only swallowtail in the U.S. that doesn't have tails. This butterfly is sometimes called the gold-rimmed swallowtail as well for the row of yellow patches on the edges of its wings. Their larval food are pipevines, species of Aristolochia. In our yard they feed on the exotic Giant Aristolochia, and this year pretty well denuded the massive vine.

One year, when I didn't have any caterpillars I "imported" a batch from a friend about 25 miles north of me whose polydamas larvae were on the point of starvation after completely stripping  her Aristolochia plants.

 (The pipevine swallowtail, which also feeds on Aristolochia species, looks quite different. It has short tails, and it's deep black wings are brushed with bright blue iridescence. It has creamy patches near the margins on the upper wings, and large, bright orange patches on the undersides. It does not make it quite as far south as Collier County).

The polydamas is a strong, vigorous flyer, with a rapid, almost "nervous" wingbeat. I never have seen one basking. Even when nectaring, they keep up their fluttering, and I wonder whether they may actually feed on the wing like hummingbirds now and then. The ones in our yard fly about 5-10 feet off the ground when patrolling, swooping down mainly to lay eggs or take a sip of nectar.

Polydamas Checking Out Pipevine
Notice Hornet Patrolling lower left

This is the best year for polydamas swallowtails in our yard for a long time. The last few years a few adults have showed up, some even laying eggs. But predators seemed to clean out the caterpillars, and repeat appearances by adults were rare.

This year I noticed the first polydamas in early May, and they pretty much stayed with us through mid- July. After about a week of no sightings, I see a brand new adult as we near the end of the month. Some of the adults who emerge probably stay here, but timing of appearance suggests that I also have had some visits by newcomers.

 I have seen polydamas swallowtails here as early as late February and as late as mid-November. They range up to north-central Florida, but may stray farther north. A subspecies occurs in coastal south Texas. Otherwise, they inhabit the Bahamas, Carribean Islands, southern coastal Mexico, Central America, and south to Argentina in South America. There are many sub-species.

Polydamas Swallowtail

The above quick and dirty, and not neurotically accurate color pencil drawings were made from a battered dead specimen I picked up years ago. I'm  not at all happy with the brown undersides. I tried layering different colors, but still did not pick up the elusive, reflective warm brown/black coloration.

The female lays a cluster of orange-yellow eggs on tendrils and tender young leaves. At first the caterpillars stay close together. There must be some evolutionary advantage in this behavior, but it also makes them very vulnerable to predators. A wasp can wipe out a brood in a matter of minutes. When they get about 3/8 to 1/2 inches long they go their separate ways.

Ovipositing Female

Young caterpillars are orangish tan to brown, with many bristles. The older caterpillar looks like a fat brown slug with orange tubercules protruding from its body. The larvae absorb toxins from the aristolochia, so they are distasteful to birds and lizards. But nothing saves them from hornets.

Too many times, I have watched a hornet methodically hunting the larvae amid the leaves and devouring them one after the other. All that is left is a little puddle. I'm lucky if even one or two individuals in some broods make it to adulthood. I  have had 3 sets of egg-laying so far this years, and apart from the first brood, the hornet has been there every day looking for prey. I'm hoping it  missed one here and there, but a successful brood may depend on timing with the emergence of adult hornets and other wasps. I just don't know. The interrelationships in the natural world are so complex. And we may be getting a distorted view of it on our tiny 60x110-foot plot.

The caterpillars are sort of dumb, even for creatures that low on the intellectual ladder. I've seen more than one start eating the stem between it and the plant, and then plop down to the ground once it has severed the connection. It doesn't seem fatal, though.

Polydamas Caterpillar

One year I got fed up with the hornet's gluttony and brought several caterpillars onto the screened patio. I cut new Aristolochia leaves and stems for them faithfully, but something went terribly wrong. None were able to form a complete chrysalis, and one never got beyond the J-stage. I don't know whether I deprived my larvae of some vital nutrient by feeding them cuttings, or whether they contracted some kind of disease. Now, even though the hornet distresses me, I just leave nature to take its course.

Butterflies usually leave the host plant to pupate, but I have found a lot of chrysalides tucked in along the vine. They resemble twisted leaves, dead or alive - some are green and some are brown with orange markings. They are very "architectural," and remind me of miniature sets of armor. The brown chrysalis in the sketch below has been parasitized. The spot that looks like an eye is the hole from which the parasite emerged. The chrysalis may hang vertically or horizontally.

Polydamas adults are particularly fond of the weedy Madagascar Periwinkle(Catharanthus roseus) that has been in south Florida most likely for centuries. It flowers at the end of the stems, and doesn't start blooming before it is pretty tall. The stems quickly get 3 feet tall or more, and it takes no time at all for them to lose a lot of leaves along the way, and look leggy, scraggly and bare. That's when I cut them all the way back. By the way they show up in the yard, they produce plenty of viable seeds. I also have a pinkish-magenta form. I don't know whether the polydamas likes them because I see only the white ones from the windows. The center of the white ones usually is dark rose-magenta, but also can be green-yellow.

A member of the dogbane family, Apocnyaceae, Madagascar periwinkle is quite poisonous. It is a prime exhibit for the argument of preserving plants, for potent anti-cancer drugs have been developed from its sap. While it is a ubiquitous escape in Florida, it hasn't been classified as invasive. I hope it doesn't reach that status because many kinds of butterflies love it, and it provides clumps of cheerful, clear whites and pinks all through the year. It actually is endangered in Madagascar, its place of origin.

White Madagascar Periwinkles

When I was taking high school biology I laughed at the naivety - even stupidity - of the early theory of "spontaneous generation" to explain how animals originated. But when it comes to establishing a pollinator garden in the world of tidy, chemically-coddled suburban lawns, the possibility doesn't seem that far-fetched. Just plant some flowers, preferably natives, get some larval host plants established, and the butterflies, bees, flies and wasps show up. How they found and find me still seems pretty magical. Sadly, in the 26 years we've lived here, the sheer numbers and the number of species have declined, but I'm not giving up just yet.

Good Sources of Information:

Emmel & Kinney. Florida's Fabulous Butterflies. World Publications. 1997.

Gerberg & Arnett. Florida Butterflies. Natural Science Publications. 1989.

Glassberg, Minno & Calhoun. Butterflies Through Binoculars: Florida. Oxford University Press. 2000.

Hall. Polydamas. This article is particularly informative. I tried to create a link, but had no success. You can find the article just by searching "polydamas" and scrolling to it.

Minno & Minno. Florida Butterfly Gardening. University Press of Florida. 1999.

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