Alternative hypotheses for the ancestor-descendant relationships among the orders of the winged insects will be tested using 18s ribosomal RNA analysis. Mapping, sequencing and development of a gene library using six species representing several orders will provide data for cladisitc analysis. The proposed research will be an independent test of insect relationships formerly interpreted using only morphology, thereby clarifying a long-standing and important evolutionary question. The research will also contribute to the growing database in molecular systematics.