Swallowtail  (Papilio machaon britannicus)

The swallowtail produces a single brood a year in the Norfolk Broads, but a second brood may be produced in some years (4). The sole foodplant is milk parsley (Peucedanum palustre) (3). Adults are on the wing from late May to mid July, and second brood adults are present in August (4). Females lay their eggs singly on the leaves of milk parsley and the caterpillars hatch out after around one week. They are active during the day and feed on the foodplant for about a month until they are fully grown. If disturbed, a pair of bright orange scent glands emerge from just behind the head; these horn-like structures repel potential predators by the strong unpleasant smell that they emit (3). The caterpillars attach their pupae low down on plant stems; the adults emerge either within three weeks, or after hibernating through the winter (3).