The reactions of three Drosophila species (D. melanogaster, D. simulans and D. immigrans) were studied in a temperature gradient at different humidities. In a saturation-deficit gradient all three species showed adaptive behaviour which could be related to their physiological resistance to desiccation. This is taken as experimental evidence for similar avoidance of stressful conditions in the field.

P. persimilis is a recently discovered Australian parasitoid of several cosmopolitan and native species of Drosophila. It can be reared in the laboratory, and has a life cycle similar to that of other Hymenopterous insect endoparasites. An egg is laid in the host larva, and the adult wasp emerges from the host puparium. Various aspects of the wasp's behaviour and physiology, especially those features which may affect its relationship with its host in the field, were investigated in laboratory experiments. The results indicate that P. persimilis has many attributes which (potentially) allow it to be a very efficient parasitoid.

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