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The new world screwworm [Cochliomyia hominivorax (Coquerel)] was eradicated in North America, Libya and other locations using the sterile insect technique (SIT).

To examine the role of weather in its eradication, a physiologically-based demographic model was developed and used to characterize its range of year-round persistence. Published data on developmental times, fecundity and mortality rates on temperature were used to parameterize the model. The lower and upper thermal thresholds for development are 14.5 and 43.5 degrees C, and the optimal temperature for survival is 27.2 degrees C. An index of favourability based on annual rainfall was used as an approximate estimate of the limiting effects of moisture in arid areas.

The open source geographical information system software grass was used to map the simulation results, as well as county level myiasis incidence data for Texas for the 1962-1983 SIT eradication programme.

Winter temperature and rainfall are shown to have a strong influence on screwworm outbreaks and in facilitating eradication in North America and Libya. Prospective analysis for the Mediterranean Basin suggests that eastern areas are most favourable for screwworm establishment (e.g. the Nile River area of Egypt).

The SIT eradication programme and its possible extension into South America are discussed.

Expected +2 degrees C climate warming is predicted to increase the potential year-round range of screwworm in the southeast U.S.A.