Photomacrograph of the head of a Swallowtail butterfly (Papilio). Two compound eyes (for accurate perception of movement), two antennae and a long, curled proboscis (feeding tube used to drink nectar from flowers) are visible. Swallowtail butterflies are widely distributed around the world and are often found in wetlands such as marshes and fens. They get their name from characteristic hindwing extensions which are reminiscent of a swallow's tail. Width of image is 5 mm. Wellcome Image Awards 2016.