Scarce Swallowtail

Both sexes are usually encountered singly. Males visit seepages and patches of damp soil where they imbibe mineralised moisture. At such times they keep their wings firmly closed.

Females are more often seen nectaring at the flowers of trees and bushes including apple, pear, cherry, lilac and Buddleia, but also visit herbaceous plants including valerian, bugle, thistles, knapweeds, ragwort and stonecrop. When nectaring the wings are usually held at a 45° angle.
Iphiclides podalirius is polyphagous.
The caterpillars spin little pads on leaves and grip them firmly. The newly hatched caterpillar is dark in colour with two smaller and two bigger greenish patches on the dorsal side, later they are greenish with yellowish dorsal and side stripes. The summer chrysalids are green as a rule, the hibernating ones are brown. A number of hibernating chrysalids fall prey to various enemies.
The caterpillars of the Scarce Swallowtail have been noted to leave silk trails from the permanent resting sites to feeding sites. This has been seen in both solitary and territorial larves with larvae having the ability to discern their trails from those of others.
Research on pupae of Iphiclides podalirius in Spain indicates that the pupae manifest in two colours, green and brown, for the purpose of camouflage. The green pupae develop on hostplants and develop directly while brown pupae enter into diapause in the leaf litter. Pupating larvae tend to form green pupae before August while after August they tend to form brown pupae.