Old World Swallowtail

The food plants of the swallowtail in Europe, Asia, and North America are varied. It uses a wide variety of umbellifers including wild carrot (Daucus carota), wild angelica (Angelica sylvestris), fennel (Foeniculum vulgare), and hogweeds (Heracleum). In the Maltese Islands, the caterpillar feeds on plants such as rue (Ruta chalepensis) and fennel.
The caterpillar spends the first part of its life with the appearance of a bird dropping, an effective defense against predators. As the caterpillar grows larger, it becomes green with black and orange markings. It has a defense against predators in the form of an osmeterium, which consists of retractable, fleshy projections behind its head that can release a foul smell if disturbed, which deters insects, but not birds