Flying insects can use volatile attractants to find food, mates, and oviposition sites. To gain understanding of the behavioral mechanisms involved, three questions were studied: how do insects find attractants, how do they maintain contact with attractants once found, and how are attractants used to locate resources that emitted the attractants. The study focused on the role of two senses, vision and olfaction. Chapter 1 presents the current knowledge of odor-mediated flight, the methods of study, and a general outline of the studies presented in later chapters. In Chapter 2 the precision of an existing measurement system for flight behavior is compared with a system developed as part of this dissertation. This new system can reconstruct flight in three dimensions. Chapter 3 proposes a novel approach to the description of flight behavior using a set of mutually exclusive and collectively exhaustive maneuvers obtained with cluster analysis of measurements derived from flight tracks. Responses to changes of the floor pattern by the parasitoid Microplitis croceipes and the gypsy moth Lymantria dispar are compared in Chapter 4 to further the understanding of the role of vision during odor-mediated upwind flight. Chapter 5 described how flight of M. croceipes is affected by increases in wind velocity. Studies presented in Chapter 6 with tagged L. dispar show in greater detail than was possible before, how this moth species controls direction of flight in increasing winds. In Chapter 7 a test of a model for responses to shifting winds to optimize plume location is presented, using flight responses of two species of food-deprived fruitflies, Drosophila funebris and D. immigrans. The effect of changes in contrast of the floor and removal of the host-odor plume on flights of M. croceipes measured in 3-D are presented in Chapter 8. Chapter 9 demonstrates that M. croceipes uses transverse chemotaxis to maintain contact with a host-odor plume.