Receptor for ecdysone. Binds to ecdysone response elements (ECRES). It is found in both larval wing disks and pupal wings and in prothoracic glands. In the wing disks levels increase on day 2 fifth larval instar reaching a maximum on day 5, and then decrease sharply on day 6. In the prothoracic glands levels increase sharply on day 2 then remain high throughout the larval-pupal transformation and after pupal ecdysis. Belongs to the nuclear hormone receptor family. NR1 subfamily.