A Bactrocera oleae genomic library was constructed and several genomic clones bearing hsp70 sequences were isolated. All clones were in situ hybridized on the major heat shock puff locus of the salivary gland polytene chromosomes. Restriction mapping of the isolated clones and genomic Southern hybridization indicated the presence of several putative hsp70 genes organized in a single cluster. Sequence analysis of an hsp70 transcription unit revealed a single 1905 nt long open reading frame that exhibits characteristic features of the inducible members of the HSP70 family. The presence and organization of many typical binding sites for the Heat Shock and GAGA factors suggest that the promoter of this gene is highly heat-inducible and could be used for conditional expression in transformation systems.