目的 了解海口市蝇类密度、种群结构和季节消长情况，为蝇类及其传播疾病的防控提供科学依据。方法 采用笼诱法，于2011-2016年在农贸市场、餐饮店外环境、绿化带、居民区4种生境连续进行蝇类种群密度监测，每月监测1次；运用Excel 2010和SPSS 16.0软件进行数据整理和统计学分析。结果 2011-2016年共捕获蝇类24977只，平均蝇密度为16.63只/笼；大头金蝇为优势蝇种，占捕获总数的43.58%；每年的4-9月蝇密度较高；不同生境平均蝇密度以绿化带最高，为25.04只/笼，餐饮店外环境最低，为13.18只/笼。结论 2013年后海口市蝇密度下降明显，但仍应加强环境治理，及时清除蝇类孳生地，同时在高峰期采取有针对性的防治措施，以降低蝇密度。

Objective To understand the density, population structure and seasonality of flies in Haikou city, for the purpose of providing scientific basis for prevention and control of flies and fly-borne diseases. Methods The density surveillance of flies was conducted once a month using cage trap method from 2011 to 2016. Each surveillance site covered 4 habitat types, including the farmer's market, the external environment of restaurants, the green belt and the residential area. Results There were totally 24 977 flies captured during 6 years, and the average density of flies was 16.63 flies per cage. It was showed that Chrysomya megacephala was the predominant fly species (with a percentage of 43.58%). The period with the highest fly density was from April to September every year. The average density of flies of the green belt was the highest (25.04 flies per cage), while that of the external environment of restaurants was the lowest (13.18 flies per cage), among different habitat types. Conclusion The density of flies declined significantly in Haikou city after 2013. However, the environmental management should still be strengthened in the future and the breeding places of flies should be removed timely. Meanwhile, targeted control methods should be taken during the peak time, in order to reduce the fly populations.