The Aristolochia vine swallowtails
By James Maxwell Overton
Some of the largest and most beautiful butterflies in the world belong
to a group called the "swallowtails". Most of the species have tails on their
hind wings which may be extraordinarily long. Others have no tails but are still included
in this group because of other features. The species that feed on the Aristolochia vine
are sometimes referred to as poison-eaters, because of the poisonous chemicals found in
the vines, and in the Townsville area include the birdwing, the big greasy, and the
red-bodied
swallowtail.
The birdwing, Ornithoptera priamus , is a truly spectacular butterfly
in its natural habitat. It is not an exaggeration to refer to these butterflies as
"birdwings" as their wing-span of up to 18 cm exceeds that of many small birds.
The species is strongly dimorphic, which means that the males look very different from the
females. The female is larger, though its sombre colouring of black, yellow and white
often combine to make it less obvious. The male on the other hand is resplendent in
brilliant green, black and gold, and catches the eye as it flaps slowly through the
garden.
The big greasy (Cressida cressida ) is common all along the east coast
of Queensland. Their wings are partly transparent, being almost devoid of scales, and the
light glinting off their wings gives them a greasy appearance which has given rise to
their common name. The sexes are similar in size, about 8 cm across the wings, but again
the male is more eye-catching. The male's frontwing is mostly transparent with black
markings, but the hindwing is black with a large white patch and beautiful red spots. The
female has similar markings but in a washed out brown instead of black.
The red-bodied swallowtail (Pachliopta polydorus ) is far less common.
It occurs in some numbers around Cape York, but is rarely found south of Townsville. They
are rainforest butterflies and are seldom seen far from the margins, although they have
been recorded in Eucalyptus forest on Magnetic Island. I have seen them feeding on Lantana
flowers on the roadsides in Paluma. The sexes are similar in this species, and in size and
appearance resemble the male big greasy. The frontwing though, is not transparent, but is
black with white streaks and elongated white spots. As the common name suggests, the sides
and tip of the body is a beautiful rose-red.
All three of these swallowtails feed on vines belonging to the genus
Aristolochia , or pipe-vines. There are a number of species of these vines, and the larvae
of the butterflies often show a preference for one or more of them. Larvae of the birdwing
will feed readily on Aristolochia tagala , which is usually available through garden
centres. The plant also grows readily from seed, so if you know someone with a vine, it is
a simple matter to propagate your own. The birdwing caterpillar will also feed on a
coarser-leaved vine called Aristolochia deltantha , and will accept other species. It
does, however, take quite a bit of vine to feed each caterpillar, and small plants are
often stripped of leaves and killed. The vine grows rapidly though, and if planted near a
suitable trellis or fence, will soon be large enough to feed many larvae. I have a number
of plants in my garden, growing on fences and up trees. The eggs are large and yellowish,
and are laid singly on the under-side of the leaves. The caterpillars are a velvety brown
or black with long fleshy spines. Pupae are usually found attached to the underside of
leaves or to the stem of the vine, though caterpillars will sometimes crawl onto another
plant when they are ready to pupate.
Big greasy's also feed on A. tagala in gardens, but in the wild will
feed on small low-growing or trailing vines including A. pubera and A. thozetii. These
vines can sometimes be found and used as a source of seed. As the caterpillars are much
smaller than birdwing larvae, they need less to eat and can survive quite well on these
smaller vines. The egg is small, but is yellowish like the birdwing's, and is also laid
singly on the foodplant. Mature caterpillars are very variable in colour, but are usually
a reddish brown, often mottled with white, and have soft fleshy bumps along their body.
The pupa is similar in colour and is usually found on the vine.
The red-bodied swallowtail caterpillars also feed on A. tagala and
A.thozetii. Their eggs, caterpillars and pupae are similar to the big greasy's. It is a
relatively simple matter to make your garden attractive to these butterflies. Planting an
A. tagala vine on a fence or under a tree will almost certainly attract passing big greasy
females. Birdwings may be more difficult unless they are already in the area. These giants
prefer denser, moister vegetation, and may not venture far from it. However, when the
conditions are right, they will move in. Red-bodied swallowtails are a bit of a gamble.
They are not common anyway, but if they are occasionally to be found this far south,
providing their larval foodplant might persuade them
to stick around.
A word of warning though. There is an introduced vine, A. elegans or
Dutchman's pipe vine, that looks a bit like A. tagala but that will kill any caterpillars
eating it. Most plant nurseries are aware of this problem now, and probably no longer
stock it, but be careful.
Having planted a suitable larval foodplant though, we must also make
our gardens attractive for the adult stage. Nectar plants are also necessary. Many species
of Eucalyptus , Melaleuca , Leptospermum , Callistemon and mistletoe are useful native
plants to have in the garden, but we should not ignore the smaller "weeds" that
are often pulled out during gardening. I have observed all three swallowtails feeding on
snakeweed and Lantana , as well as introduced flowers like Ixora , Pentas, and periwinkle.
I have found that trees like fiddlewood and the strawberry tree are also very attractive
sources of nectar for many butterfly species. Sometimes we have to compromise a truly
"native" garden if we want to attract and keep butterflies in a relatively small
area like a suburban garden or small rural block.
Copyright © 1998,1999 JM Overton
