胃蝇（学名：Gasterophilinae）是一种形似蜜蜂的蝇类。成蝇体表密被黄褐色或黄白色长绒毛。幼蝇红色，前尖后钝，分节，每节常有刺1—2行，寄生于马、驴、骡等的食管、胃、肠处。严重侵袭时能使胃部运动及分泌发生障碍；又能分泌毒素，引起宿主贫血。因幼虫的寄生、钩刺，损伤粘膜，可招致继发性细菌感染。分布于中国的胃蝇，除本种外，尚有赤尾胃蝇（G.haemorrhoidalis）、黑腹胃蝇（G.pecorum）、烦扰胃蝇（G.veterinus）、无刺胃蝇（G.intermis）。

The Gasterophilinae are a subfamily of Oestridae which includes large, parasitic flies; this group has historically been treated as a family, but all recent classifications place them firmly within the Oestridae. Many members of this subfamily spend part of their larval stages in the digestive tracts of herbivores. The best known genus is Gasterophilus, which attacks horses, deer, and similar animals. The genus Cobboldia breeds in elephants. The genus Gyrostigma breeds in rhinoceroses.