Photoproject Swallowtail

Tthe Swallowtail (Papilio machaon)


The swallowtail is BIG GAME, I always look for it though it has become extinct in Denmark, or maybe because of that. Sometimes migrating specimens are observed. So one day....


  I have never seen it in Denmark, yet, but I have seen it in Sweden, Poland, Germany, France, Italy, Switzerland and Greece. In Sweeden as in southern Europe it relatively abundant. You meet single Swallowtails at flowers in gardens, along roads, in meadows with flowers or it flies by when the family is at the beach.

The Swallowtail is a powerfull flier and lives a migrating life. Many butterflies are rather local and stay in their place. Nymphaldae can often be seen resting and sunbathing at the same treetrunk or stone several days in a row.

Swallowtails are not like that. They follow lines ind the landscape: along a road, a cliffside or a river. With pitstops at flowers along their route the y fly fast and straight through the landscape. Some places, like at a group of nectar rich flowers close to a cliff or a hilltop there can be several swallowtails gathering.

Swallowtail, Alsace, Keyserberg, 17. July 2006.
Flight season and abundance  
The Swallowtail is widespread in Europe. From the north of Scandinavia to the south of Spain. I occurs in the eastern parts of United Kingdom but does not reach Ireland.  

The Swallowtail is a typical Peridae and overwinters as a chrysalis. Dependant of the lenght of the summer it occurs in 1, 2 or 3 generations throughout the summer.

The Swallowtail emerges in early spring at the same time as the peridae, fx A. cardamines, when the warm weather has come to stay and the dandelions are in blosom.
Not all Swallowtails emerge at the same time, some are delayed, and you can find first generation Swallowtails till the beginning of July.
Swallowtail Haute Saone, 15. July 2006.

The caterpillar of the Swallowtail lives on a variety of Umbelliferae and certain species are preferred in certain areas.

To the left is a lake in France with a few Umbelliferae at the banks. Below a bucket of flowers on the Hilltop. The swallowtails flew along the lake banks and ended up at the flowers at the hilltop.

  The Umbelliferae at the lake banks were one of many breeding places for the metapoulation and the flowers were one of the nectar sources.
Swallowtail "nectar source", Ronchamp, Haute Saone, 16. July 2006.
Habitat, Haute Saone, 16. July 2006.
Specific adaptions
  In Scandinavia and England the Swallowtail is connected to hogs and fennels and the females prefer to lay on Peucedanum palustre. Certain Palces in Costal Sweeden the caterpillars feed on Angelica archangelica ssp. littoralis.

Swallowtails can be found everywhere where there are appropriate host plants, and that is excatly the problem: Natural Umbelliferae populations have always been scarce and spread over large areas, so the Swallowtails are adapted to fly long distances.

If the number of suitable Umbelliferae falls, and the distance between them becomes to far a few things can go wrong:

  Finding a mating partner takes more time and is less likely to happen and the warning colours of caterpillar and imago will not work. The swallowtail wears warning colours. Both Imago and the caterpillar depend on a real warning and a threat of the poison the caterpillar took in by eating poisonous Umbelliferae. But warning colours only work if the bird recognizes them. If there are too few Swallowtails the birds wont learn the specific pattern of neither the caterpillar or the Imago..
Swallowtail Haute Saone, 16. July 2006.
Larval Hostplants and Nectar Sources
The Swallowtail needs a large area with both nectar sources and an abundance of larval host plants. It does not matter much what is in between, it can be water, urban areas or mountains. The Swallowtail can cross the hostile areas as long as they are not too wide and lies inside a pattern of suitable habitats.  
Swallowtail Alsace, Keyserberg, 18. July 2006
The caterpillar
Swallowtail caterpillar. Gotland, Sweden, July 2006
Swallowtail caterpillar. Gotland, Sweden, July 2006
The chrysalis  

As seen on the pictures the Caterpillar of the Swallowtail is very colourful and easy to find. It often sits in the top of the host plant.

The mature caterpillar wanders away from the plant at hides under a leaf for pupation.
  The pupa is poisonous as the other instars, but as it sits still it cannot display any warning behaviour and it is therefore camouflaged. The chrysalis comes in three variations: a green one as to the left, a pale brown and a contrasted light grey and black.
Chrysalis of Swallowtail, Gotland, Sweden, July 2006.
Close up of the caterpillar  
Swallowtail caterpillar. Gotland, Sweden, July 2006
The photo is taken with a 50 mm macro lens towards the blue sky while the caterpillars sat sleeping in the sun.