GAL4 is a well-established binary transcription system that can provide a level of modularity to expressing transgenes in specific patterns. Tsubota et al describe the construction of GAL4 transgenes under the regulatory control of promoters from genes with strong expressing in hemocytes. One of these promoters drives expression strongly and specifically in oenocytes.
Tsubota, T.; Uchino, K.; Kamimura, M.; et al. Establishment of transgenic silkworms expressing GAL4 specifically in the haemocyte oenocytoid cells. INSECT MOLECULAR BIOLOGY, Volume: 23, Issue: 2, Pages: 165-174, DOI: 10.1111/imb.12071