The ecdysonreceptor is studied from a multi-disciplininary research effort (molecular - cellular - fysiological) in the unique developmental process of metamorphosis in insects.The purpose is to gain insight in the presence and diversity of Ecr in different insect species en regulating factors. Through this molecular basis we attempt to better understand the unique character of metamorphosis in insects. The ability to intervene on a new and insect-specific target site offers valuable and human/environmentally friendly future possibilities in combatting important and resistant plague insects.