Transcription factor required for ecdysteroid production in the prothoracic gland by activating transcription of the ecdysteroid biosynthesis gene spok. Binds to the 5'-AGCTTTATTATTTAG-3' DNA sequence in the spok enhancer region. Expressed predominantly in the prothoracic gland during embryonic and larval development. During larval development, expression is low during early stages and gradually becomes higher in late stages. Larval developmental arrest due to ecdysteroid deficiency. The name 'ouija board' derives from the instrument used for calling ghosts and is based on the fact that mutants cannot induce expression of the ecdysteroid biosynthesis protein spookier. Extended N-terminus.