Abstract: Objective  To observe the effect of diets with different fat levels on the body size and development of Lucilia sericata.  Methods  Under the constant temperature of 28 ℃, the larvae were reared on the diets containing 0%（G0）, 10%（G1）, 30%（G3）, 50%（G5） and 80%（G8） fat tissues（fat/muscle ratio）, respectively. Length and weight of larvae and pupae were measured at 12 h interval since 16 h after eclosion. Length of inter-medial cross vein（m-m） of adult left wing was measured. 10 samples were collected in each group. The developmental duration time, mortality and sex ratios of adults were recorded.  Results  The mean maximal larval length［（13.3±1.2）, （12.0±1.1）, （10.2±0.9） and （8.8±0.8） mm, respectively］ and mean maximal larval weight［（72.8±6.1）, （62.2±5.7）, （47.2±4.3）, and （34.9±5.7） mg］ in G1, G3, G5 and G8 groups were significantly less than that of the G0 group［（14.8±1.3） mm and（80.4±8.1） mg］（P<0.01）. The body size of pupae and adults was also significantly less than that of G0 group（P<0.01）. The total duration time of G5 and G8 groups ［（293.3±22.2） and （285.2±24.6） h］ were significantly shorter than that of G0 group ［（312.8±20.1） h］（P<0.01）. The mortality of larvae ［（32.6±5.6）% and （44.3±7.7）%］ and pupae［（28.6±5.5）% and （43.5±6.2）%］ of G5 and G8 group were also significantly higher than that of G0 group［（5.7±3.3）% and （4.5±1.9）%］（P<0.01）. There was no significant difference in sex ratio among the 5 groups（P＞0.05）.  Conclusion  The body size of larvae, pupae and adults of Lucilia sericata is smaller, the development time is shorter and mortality is higher when the food substrate contains more fat tissues.

Key words: Forensic entomology, Lucilia sericata, Developmental duration, Food source, Fat