INFLUENCE OF CONSTANT AND CHANGING TEMPERATURE AND HUMIDITY ON THE DEVELOPMENT AND SURVIVAL OF THE EGGS AND PUPAE OF DROSOPHILA-MELANOGASTER (MEIGEN)

1. The mean durations of development in the eggs and pupae of Drosophi la melangoaster (Meigen) and their survival, were measured at combinat ions of six constant temperatures and up to eleven levels of vapour pr essure deficit. 2. Temperature was found to account for from 58 to 98% of the variation in the mean duration of the development, whereas vap our pressure deficit (or relative humidity which is the opposite scale ) accounted for from 43 to 91% of the variance in the survival of the two stages. 3. Vapour pressure deficit was found to be highly positive ly correlated with the mortalities of both stages, thus relative humid ity was highly negatively correlated with both stages. 4. No significa nt extra effect on the development of the egg and pupal stages was evi dent when they were subjected to two different sets of temperature/hum idity conditions for 12 h periods each. The present results can be use d as a basis for modelling the development of these stages under chang ing conditions of both temperature and humidity.