This protein binds a chromophore: biliverdin IX, isomer gamma. Mixed with lipoprotein-bound carotenes, this blue protein provides hornworms with their green cryptic coloration which serves a camouflage. Homotetramer. Synthesized only in the caterpillars, apparently by the epidermis and secreted into the hemolymph. The protein is passed over from the larval hemolymph to that of pupae and adults and is sequestered in the eggs. The molecule consist primarily of eight antiparallel beta-pleated strands, which enclose a hydrophobic pocket, and an alpha-helix. Belongs to the calycin superfamily. Lipocalin family.