Butterfly vines and Swallowtail butterflies

We have been growing a particular vine, for years, just for the Birdwing butterflies whose caterpillars depend on it. Just what the vine is called and which butterflies depend on it are, however, recurring questions – for us as well as for the many other people who love the butterflies. This post pulls together information from botanical and entomological books and websites to try to settle both questions.

Very briefly, all species of butterflies in one group of Swallowtail butterflies have specialised to feed exclusively on one group of closely related plants. The butterflies are the Troidini, a “tribe” (in scientific language that’s a level between “family” and “genus”) of Swallowtails (Papilionidae) and the plants are the Birthworts (Aristolochiaceae).

Our Troidini are the Clearwing Swallowtail (Cressida cressida), Red-bodied Swallowtail (Atrophaneura polydorus) and all of the Birdwings (Ornithoptera species). The Aristolochiaceae we’re interested in are in the genus Aristolochia, or used to be, and many of them are known as Dutchman’s Pipe vines.

caterpillars of clearwing and birdwing butterflies
Caterpillars of Clearwing (left) and Cairns Birdwing butterflies, both nearly fully grown, on Aristolochia tagala

Everything gets messy at the next level of detail. If you want to avoid that but still attract the butterflies to your garden, this is all you need to know:

  • Aristolochia tagala, also known as Aristolochia acuminata,  is a food plant of all our Birdwing species and of the Red-bodied and Clearwing Swallowtails, and it is the one most widely grown in Townsville gardens. It is sold by the Bush Garden Nursery as A. acuminata.
  • Richmond Butterfly Vine, Pararistolochia praevenosa, is a food plant of all  Birdwing species and the Red-bodied Swallowtail. It is the vine widely promoted in SE Queensland as the “birdwing butterfly vine.”
  • Dutchman’s Pipe Vine, Aristolochia elegans also known as A. littoralis, is the one to avoid. It’s an exotic, introduced from South America, and it poisons our butterflies. The adults lay their eggs on it but the caterpillars rarely survive.
  • If you stick to the Latin names, there should be no confusion about which vine is which.

Here are the flowers of the three vines:

Aristolochia flowers
Three pipevines, from the Butterfly House site

Why and how do scientific names change?

Latin names of every species from fleas to cassowaries and from oregano to mountain ash are usually given as two words, Genus species, and organisms are formally named by the first person to fully describe them in a scientific publication. If there are slight variations within the species, it might be divided into subspecies, so the name is lengthened to Genus species subspecies. That’s clear enough, of course, but then someone else comes along …

  • If one genus appears to be too similar to another, they can be merged under whichever name came first; in that case, all species (second) names stay the same.
  • If some species in one genus are seen to be too different from each other, the genus can be split; some organisms will get a new genus (first) name.
  • If some subspecies begin to look different enough from others, they can be promoted to species ranking; they will lose their middle name.
  • It may be noticed that the same organism has been described and named twice; the first name is given priority and the other, the “synonym”, is (gradually) abandoned.
  • Similar changes can be made at higher levels of classification, such as  Family, Superfamily and Tribe, but they are not as common.

This blog has discussed these sorts of changes in relation to the Koel and Melaleucas, among others, over the years. They don’t happen very often to any one species but with millions of species to look out for, keeping track of the names is a big job; see, for instance The Plant List.

There are, of course, no limits or rules on common names.

The butterflies

The simplest way to sort out the butterflies is to quote the list given on the Butterfly House site and add alternative names to it as required. Links lead to species pages on that site, with photos of adults and caterpillars, so following them should resolve any uncertainties.

Braby comments that, “Much confusion and controversy has surrounded the taxonomic status,” of our Birdwings. He lists them all as Ornithoptera, mentioning that they were previously known as Troides. (Troides has recently been split into Troides, mostly Asian butterflies, and Ornithoptera.)

Braby divides Ornithoptera into only two species, priamus and richmondia, but divides priamus into four subspecies, calling the Cairns Birdwing Ornithoptera priamus euphorion. Others have named as many as 19 subspecies, while Wikipedia : Birdwing takes a middle position, listing three Australian species (euphorion, priamus and richmondia) under Ornithoptera.

The Richmond Birdwing lives so far South of any of the others, in a small coastal area near the Qld-NSW border, that it can’t be confused with them. The other/s have a patchy coastal distribution from Mackay to Cape York, new Guinea and the Pacific islands, and the debate over their names is really about whether local differences are big enough to justify calling them subspecies or species.

What all that means to us is that anything called either Troides or Ornithoptera but not richmondia is one of our NQ Birdwings and it is very closely related to all the others. Since they all look so similar and all feed on the same plants, that’s not a bad outcome. “Cairns Birdwing” is probably the least controversial name for them.

The vines

Aristolochiaceae includes both Aristolochia and Pararistolochia. Species in the latter were included in Aristolochia until the genus was split in 1996, so many older references will still have, for instance, Aristolochia praevenosa rather than Pararistolochia praevenosa. There are hundreds of species in these two genera worldwide but fortunately we are only concerned with a dozen of them.

Here’s a composite list based on the Butterfly House site but cross-checked with Braby’s book and a list prepared by Peter Valentine. The first two are the most important to us because they are the most readily available.

  • Birthwort, Aristolochia tagala also known as A. acuminata. If anyone uses a common name for it, it will probably be “Native Dutchman’s Pipe”, but really it is better to use the Latin name.
    * This is a food plant of all Birdwing species and of the Red-bodied and Clearwing Swallowtails and it is the one most widely grown in Townsville gardens. It is sold by the Bush Garden Nursery under the name A. acuminata, a synonym of A. tagala.
  • Richmond Butterfly Vine, Pararistolochia praevenosa
    * All Birdwing species and the Red-bodied Swallowtail. This is the vine widely promoted in SE Queensland as “the birdwing butterfly vine”.

These other native (i.e., good) species are all listed for some of our butterflies but not for all of them. However, the differences seem to be mainly geographical, e.g., the vine can’t be listed for the Richmond Birdwing if it only grows on Cape York.

  • Mountain Aristolochia, Pararistolochia deltantha
  • Indian Birthwort, Aristolochia indica
  • Chalmer’s Birthwort, Aristolochia chalmersii
  • Australian Native Dutchman’s Pipe, Aristolochia thozetii
  • Cairns Birdwing Butterfly Vine, Pararistolochia australopithecurus
  • Heathlands Aristolochia, Pararistolochia linearifolia
  • Cape York Birthwort, Pararistolochia peninsulensis

Most of them are rainforest plants and several have alternate names. Aristolochia thozetii and Pararistolochia deltantha are  worth special mention in that they are local (well, Paluma Range) and have attractive flowers so they might be candidates for home gardens or revegetation projects.

These last two are listed only for the Clearwing:

  • Holtze’s Birthwort, Aristolochia holtzei
  • Hairy Birthwort, Aristolochia pubera

The villain

  • Dutchman’s Pipe vine, Aristolochia elegans, also known as A. littoralis.
    * This is the one to avoid! It’s an exotic, not a native, and it poisons our butterflies. The adults lay their eggs on it but the larvae usually don’t survive.
    Brisbane City Council calls it a weed and describes it fully on this page and, at the bottom, lists other exotic Dutchman’s Pipe vines which are not (yet) such a problem but should be avoided for the same reasons.

Where are our birdwing butterflies?

A friend sent me a photo of a caterpillar ten days ago, with two implied questions:

This caterpillar is feeding off native Dutchmans Pipe.

Also, the Cairns Birdwing caterpillars of several people I have spoken to have died and butterflies are scarce even though there is a plentiful food source.

The first question was easy to answer: it was a caterpillar of the Clearwing Swallowtail, aka Big Greasy, butterfly (Cressida cressida), which shares Aristolochia tagala with the Cairns Birdwing.

They are quite distinctive at every stage of their little lives. The tiniest ones are orange; a little later they are maroon with white spines; and finally they are creamy-white with some maroon markings, as in this old post.

Continue reading “Where are our birdwing butterflies?”

Birdwing emergence

When they are ready to pupate, Cairns Birdwing caterpillars drop off the Aristolochia vine they had been eating and climb a neighbouring plant. There they find an appropriate twig or leaf, reinforce it with some of their silk, make a sling with more silk, and hang there in their new hard brown skin (which is what the chrysalis is) while they miraculously re-organise inside it (see this blog post for more details). When the time comes …

cairns birdwing butterfly
Just out – wings still damp and collapsed

Continue reading “Birdwing emergence”

Birdwing butterflies again

I posted a photo of a male Cairns Birdwing a couple of weeks ago with the comment that they are so common that “I rarely bother pointing a camera at them.” As usually happens in such cases, I proved myself wrong soon afterwards.

The occasion was my sighting of a female which I thought might be of the Northern species, the New Guinea Birdwing (Ornithoptera priamus), which shouldn’t be seen in Townsville according to the books. I then wanted to check that the local males weren’t (also?) New Guinea Birdwings but that meant getting a good look at the upper surface of the wings, which is not at all easy.

Birdwings and Ulysses on any rack of tourist-trap postcards lie around with their wings gaudily spread but in real life they do nothing of the sort. The wings slam shut as soon as they perch, presenting their much more discreet undersides to the gaze of predatory birds. Almost the only way of getting a photo of the upper sides from a wild swallowtail is to take a burst of shots of a hovering butterfly and throw away most of them. That’s how I got this one.

Cairns Birdwing
Male Birdwing butterfly

There are a few points of interest:

  • Getting a really sharp, clear photo by this technique is a fluky business. You need lots of light so the shutter speed can stay high enough to freeze the movement (I didn’t have that luxury), and enough shots that at least one of them is well composed.
  • It is definitely a Cairns Birdwing, not the northerner, because the large central black area has no green streak through it. That’s a little disappointing but not surprising.
  • The wings are catching the light at very different angles and show the same kind of apparent colour-change as the Eggfly. In this case, the bright yellow-green of the wing becomes bluish-purple when seen at an acute angle; it can look even more purple in flight, depending on the angle of the sun.
  • And this is an old, battered individual. The trailing edge of the left fore-wing is ragged, and the coloured areas have scratches where scales have been scraped off. This sort of damage is why I noted that the Lurcher (click here and scroll down) was rather elderly.

Cairns Birdwing butterfly pupation and emergence

caterpillar hanging from leaf
Beginning pupation. Note how the leaf and stem have been reinforced with black silk.

I have been writing about Cairns Birdwing butterflies quite often but there are still more things to say (and our visitors always seem delighted and fascinated by them) so I will keep adding to the story.

Pupation, the process of forming the chrysalis, changing inside it and emerging as an adult, is one of the most  baffling processes in nature. I’m not even going to speculate about how an insect could have evolved such a bizarre practice but want to share my observations of the beginning and end of it.

Birdwing caterpillars eat until they are big enough and then leave the vine they have been feeding on and attach themselves to a nearby plant, often a metre or two off the ground (sometimes they drop from the vine to the ground to crawl up the stem of another plant). The one in my first photo chose the twig of a rose bush and I was intrigued to see that it reinforced the rose with strands of silk running down from the branch, over the leaf and around the twig – a sensible precaution against the leaf falling off, of course, but again one has to wonder how it evolved (as usual, click the photo to see it better). It then made a silk sling from the plant around what would be its shoulders if it had shoulders, and hung tail down for a surprisingly long period – a couple of days.

But how do they get into their chrysalis? I have to admit to relying on vague memories of silkworms, but those memories put me on the wrong track entirely because they don’t “get into” the chrysalis at all. Rather, they form it under their skin, then shed the skin just as they have already done several times during their growth as a caterpillar.

birdwing butterfly chrysalis
A very new chrysalis, with the discarded skin still dangling from it.

I actually woke up to that – and to my own ignorance – when I saw a fresh chrysalis, not yet hardened, flexing to shrug off the last part of its skin. In this second photo (not the same caterpillar, of course) you can see the crumpled skin, complete with head-shell and legs, still barely attached to the chrysalis.

A related point is the difference between a chrysalis and a cocoon. As Museum Victoria point out here,  “the skin that emerges from under the old skin is a chrysalis. Both butterflies and moths develop a chrysalis in their pupal stage, but the chrysalises of moths are usually contained inside a woven structure made of silk – a cocoon.” Silkworms are the caterpillars of moths so they form cocoons around their chrysalises in just this way – see Wikipedia for more information.

The really mysterious stuff happens in the chrysalis, over the next month or so in the case of our Birdwings, and then the chrysalis splits and a damp butterfly emerges with crumpled wings. As soon as they straighten and harden, she – or he, as seen below – is off and away in search of nectar or a mate.

green and black butterfly
A male Cairns Birdwing on the chrysalis he has just emerged from
green and black butterfly flapping its wings
His first tentative wing-strokes. He flew off a few moments later