The Old World swallowtail has a wingspan of up to 100 mm. Body and wings are patterned in black and yellow. Hind wings have one red and six blue spots each. The underside is somewhat paler in color. Each hind wing has one tail. Many forms and local subspecies have been described. The relatively large compound eyes are the most important sensitive organ of the Old World swallowtail for orientation. The quality of flowers and food plants is recognized with the feet.
Culminating in a sharp, beak-like tip, the proboscis works like a straw through which a butterfly drinks its food. When a butterfly finds food, it first unfurls its mouthparts and then zips them together to form a channel. The proboscis is particularly well adapted for reaching into flowers for nectar and for piercing fruit with its sharp tip. When a butterfly is not feeding, it keeps its proboscis curled.
The photograph of the Old World swallowtail butterfly was taken in my garden yesterday. The blossom on which it is feeding is purple top vervain (Verbena bonariensis).