The swallowtail is Britain’s largest resident butterfly with a wingspan of up to 4.5 inches.

The male is often smaller than the female.

It has striking brown and yellow markings, surrounded by a blue border. A red spot marks the hind wing.

Swallowtails lay their eggs singly on milk parsley leaves. The whitish eggs mature to brown towards hatching, and small black caterpillars emerge.

Swallowtails are on the wing from mid-May to September, but numbers decline from early August.

Swallowtails will settle on nectar-rich flowers such as ragged robin, yellow flag iris and hemp agrimony.

They overwinter as chrysalises, usually on sedge and reed stems and can survive short periods of flooding.