Butterfly Education & Awareness Day: Old World Swallowtail

The 6th June is Butterfly Education and Awareness Day. To mark it, this post contains the description of the Old World Swallowtail butterfly from Historia Insectorum, which was published posthumously under the name of John Ray in 1710 but was based upon the research and work begun by Francis Willughby.

Ray gave this butterfly a descriptive name of “Papilio alis amplissimis, flavicante & nigro coloribus pulcherrime variegatis, interioribus caudatis”, which translates as “A Butterfly with Very Broad Wings, Most Beautifully Variegated with Yellowish and Black Colours, with Tailed Inner Wings”. He noted in the text that the species was so easily identified from all other English day-flying butterflies by its size and its colour that the title he provided was a sufficient description. This is true. Nevertheless, he did add that the tail was for the most part curved and above the styliform projection, it was painted with a purplish-blue colour that was continuous with the wing.

Old World Swallowtail, British subspecies Papilio machaon brittanicus, 2009. Photograph taken by LittleHow, CC BY-SA 3.0, via Wikimedia Commons.

Ray noted that he had personally observed this species: in Italy near the port of Livorno; in Gaul near Montpellier; and in the English counties of Sussex and Essex. Furthermore, he had observed its caterpillar in Sussex and near Montpellier. Ray called the caterpillar “Eruca major bicornis, flavo-viridis, annulis nigris distincta”, which translates as “A Large Two‑horned Caterpillar, Yellow‑green, Marked with Black Rings.”

Old World Swallowtail caterpillar, 2017. Photograph taken by AnRo0002, CC0, via Wikimedia Commons

The description of the caterpillar he provided stated that it was: a size between that of the Silkworm caterpillar and the Cinnabar caterpillar; a yellow‑green colour; and distinguished by black annular lines.

The lines of the rings into which the body of the caterpillar was divided were double of which the first two were entirely black, the third interspersed with six spots of a deep, saturated red-lead colour (vivid orange-red), the fourth wholly black, the fifth varied with spots and the remainder thereafter alternating black and spotted all the way to the end of the tail. The spotted lines divided the middle of the body‑rings, whilst the black ones occupied the joints or intervals between the rings.

The six forelegs of the caterpillar had black tips and the eight hindlegs were marked on the outer side with a black spot. The head was marked with four little lines and three black dots. Moreover, he commented that this caterpillar had a peculiarity. It could extend and withdraw at will, in the same manner as a snail, two intensely saffron‑coloured horns that were almost the breadth of a finger in length. Today this is known as the osmeterium and is considered an identifying feature of this caterpillar. Ray additionally noted that the caterpillar changed into a yellow‑green angular chrysalis at its first metamorphosis.

Ray commented that in Gaul the caterpillar was feeding on twisted fennel (Foeniculum vulgare) and in Sussex it was feeding on burnet-saxifrage (Pimpinella saxifraga). Furthermore, Ray provided the synonym for the butterfly of “Papilio erucae rutaceae”, by the Neapolitan naturalist Fabio Colonna, which translates as “The Butterfly of the Rue-feeding Caterpillar”.

Today, it is known that the Swallowtail caterpillar feeds primarily on plants in the parsley family. Fennel is also considered a major food source, burnet-saxifrage is recorded as a host plant and rue is an accepted food plant, especially in Southern Europe. However, it should also be noted that the caterpillar of the native British subspecies of the Swallowtail feeds exclusively on milk parsley (Peucedanum palustre), but the Continental European subspecies of Swallowtail, which also comes to Southern Britain, is more general in its diet and will feed on fennel, rue and burnet-saxifrage.

Ray also provided the synonyms of the “Diurnarum secunda a prima parum differens” (The second of the day‑flying butterflies, differing little from the first) of Thomas Muffet and the “Papilio major caudatus, ex nigro & luteo variegatus” (The large tailed butterfly, variegated with black and yellow) of James Petiver. In 1758, Carl Linnaeus gave it the name of Papilio machaon, by which name it is still known as today.

Further Reading: John Ray, Historia Insectorum, 1710, p.110.

Author - Debbie Jordan, Middleton Hall Volunteer.

Please consider supporting Middleton Hall Trust by sending us a donation.