Binds to an ommochrome, ommatin D which is a yellow chromophore. May be involved in guiding the chromophore through the hemolymph from the epidermis to the gut. Monomer. Present in larval hemolymph and synthesized by the fat body. Early larval stages produce only traces of obp, but its synthesis increases dramatically during the fifth larval instar, then it decreases but persists in hemolymph of adults.