Graphium porthaon has several English names. "Coastal Swordtail" may be the most commonly used. In some places it's the Dark Swordtail, in some the Cream-Striped Swordtail. Along with the Graphium species policenoides, liponesco, and biokoensis, it's in a group of African butterflies that look very similar to Graphium policenes but show some consistent differences.
Photos above and below by Ryan G. Fessenden.
Why are these butterflies called Graphium, anyway? Graphium is a Latin word for a writing instrument. Originally it meant a stylus, the "pen" used for punching cuneiform designs into wax. Later the word came to be applied to pens and pencils. It's yet another way of describing the long projecting ends of their hind wings.
Porthaon was a king of ancient Greece. Little is known about him. He was called a son of Ares, probably meaning a warlord. His family included a sister called Demonice or Demodice. (Whatever that may suggest in English, in Greek demo means "the people, group, tribe." Nice or Nike meant victory. Dice meant justice.)
Graphium porthaon is thought to breed and fly continuously when the weather is warm enough. In some of its range there is a cool season when eggs and pupae wait for warmer temperatures. Its range extends from South Africa to Kenya. It lives in deep, damp forests. In some places it's considered rare.
The species as a whole is not believed to be endangered. It is sometimes considered challenging to photograph. Butterfly tourism is a way some parts of Africa hope to build or boost their economies, so they allow butterfly farming to produce dead bodies for those who want to collect butterflies the oldfashioned way, and positively encourage photographing the lifeforms seen on walking tours. This issue of Metamorphosis has several articles about what can be expected on a butterfly walk, one titled "Cloudy with a Chance of Swordtails." Several nice clear photos of Graphiums, including porthaon, are scattered through the journal.
This issue has a list of the Graphiums in Kenya and what they apparently eat, the authors emphasizing that these caterpillars normally live in a tangle of vines that can make it hard to tell what they are eating and what they are merely passing over.
Its wingspan is about 3 inches, males usually under 3 inches and females sometimes a little over. The pale parts of the wings reflect light and can show a bluish, greenish, or pale turquoise cast, but usually look white to yellow.
It is not a shy species. It often flies near human habitation, and often sips water from puddles in large mixed groups, sometimes hanging out with the brighter blue Graphiums it resembles.
Photo by Clare Matake, Zambia, December 2024.
It has a wider range of food plants than many Graphiums, being able to eat leaves from some species of Artabotrys, Cleistrichlamys, Monodora, and Monanthotaxis as well as Annona and Uvaria.
There are at least three subspecies: G.p. porthaon, mackiei, and tanganyikae. Older sources may still list subspecies adjectus and vernayi, but most entomologists now consider those "synonyms."
Graphium porthaon mackiei is found in Kenya and Tanzania. I found no photographs specifically identified as mackiei.
Graphium porthaon tanganyikae is found in part of Tanzania. It is described as slightly darker than G.p. porthaon with slightly different spots on the undersides of the wings. Its range seems to be more narrow than G.p. porthaon's; the nominate subspecies has been found at altitudes from sea level to 1900m, while tanganyikae has been found between 780 and 1000m.
Photo by Butati, Tanzania, October 2021.
Graphium porthaon porthaon is found in Angola, Botswana, the Democratic Republic of the Congo, Kenya, Malawi, Mozambique, South Africa, Swaziland, Tanzania, Zambia, and Zimbabwe. INaturalist has pages devoted to each subspecies; not all are filled in, but there's quite a gallery at
Photo by Tomaschiripiburuwate, Mozambique, November 2020. Male and female often look alike.
Photo by Anibotani, South Africa, October 2024. Or females may have lower-contrast colors while males have crisper, bluer, higher-contrast colors.
Adult butterflies are thought to have about two weeks to fly,. During this time they mate, and the females lay eggs, which look like little round beads, whitish yellow at first darkening to yellow-green before they hatch.
Like all butterflies they hatch out as caterpillars, eat until they burst out of their skins into new skins a few times, then enter a motionless pupal stage during which the body undergoes enormous changes, and finally emerge as butterflies. New-hatched caterpillars look black; their skins lighten to gray or taupe as they stretch out. They are camouflaged when they hide inside flowers or along chewed edges of leaves of their host plant. Later skins are gray and then green with stripes. Final-stage caterpillars are described as green, blackish, or yellow, with bands of white, black, and yellow. They don't try to be camouflaged, but rest on the upper edges of leaves where they are concealed from most predators by more leaves.
This pupa of Graphium porthaon matured into a butterfly that flew in the Reiman Gardens but, inexplicably, the Gardens web site doesn't have photos of the adult butterflies. Graphium porthaon has also been reared and displayed at Britain's Stratford-upon-Avon butterfly gardens but their web site doesn't have a photo page.
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