A Tm1FBtr0091350:pb-XREcollacZ reporter construct with 243 bp upstream sequence, the first exon, the first intron, and 72 bp of the second exon of Tm1 was expressed in all muscles of embryo, larvae, and adults. Embryonic expression is first detected at stage 16 in visceral and body wall muscles, and the head pharyngeal muscle. Expression levels are about 80% of the level seen when 1400 bp of upstream sequence isused.