UAS regulatory sequences drive expression of a fusion protein that comprises one-half of a split sensor for endosomal microautophagy. The protein consists of the N-terminal portion of Venus fused to a microautophagy recognition motif (KFERQ). By itself, this protein is not fluorescent, but if a complementary half of the split sensor (a protein consisting of a complementary N-terminal fragment of a fluorescent protein fused to the KFERQ motif, such as Avic\GFP^{KFERQ.C-Venus.UAS}) is expressed in vivo, then when the two split halves concentrate upon targeting for microautophagy, a functional fluorescent protein may be reconstituted.