Pterobilin also called biliverdin IXγ in the Fischer nomenclature,[2] is a blue bile pigment found in Nessaea spp.,[3] Graphium agamemnon, G. antiphates, G. doson, and G.

[4] Pterobilin is a chemical precursor to sarpedobilin in the larvae of the fourth instar of G. sarpedon through a double cyclisation of the central vinyl groups of the adjacent nitrogens.

[6] In the butterfly species Pieris brassicae, it is produced starting with acetate and then proceeding to glycin, then δ-aminolevulinic acid, then coproporphyrinogen III, to protoporphyrin IX and finally into pterobilin.

[6][8] Pterobilin in P. brassicae[9][10][11] is thought to play a role in photoreception for the different instars for metering diapause.

[6] In adult P. brassicae butterflies the compound is thought to have a role in heat transfer,[12] as the wing scales where pterobilin accumulates differ morphologically in a way that would facilitate photoreception.