AbstractAdult functions of juvenile hormone (JH) have been described forDrosophila melanogasterand other dipteran insects, but preadult function for this hormone remains largely unknown in this order of insects. We have identified a mutation ofDrosophila, Methoprene‐tolerant (Met), which appears to alter JH reception during late larval development. The molecular cloning ofMetwill be a step toward understanding this gene and possibly identifying a preadult role(s) for JH. Molecular cloning was initiated using the technique of transposon‐tagging with a transposablePelement.P‐element insertional alleles ofMetwere generated, and genomic libraries were constructed from two of these alleles. From these librariesP‐element‐bearing clones were isolated that in situ hybridized to the cytogenetic region whereMethad been previously localized by genetic methods. Two of the alleles were shown to have completeP‐elements inserted in similar, but not identical, locations in the predicted cytogenetic region whereMetis located. A late‐larval cDNA library was screened to identify transcriptional units in this region, and clones were recovered with homology to a DNA fragment abutting theP‐element insertion site. These clones may representMetcDNA molecules. © 1995