A species- and egg-specific monoclonal antibody (MAb) was developed for pink bollworm, Pectinophora gossyipiella (Saunders). Positive antigen-antibody reactions were associated only with pink bollworm eggs. There was no cross-reactivity with any of the other pink bollworm life stages or with the eggs of nine other insect species examined. The use of serological procedures to study predator feeding is discussed.