寄生蝇即寄生蝇科（学名Tachinidae，又名寄蝇科）的昆虫。牠们大型及有多样性，已知有超过8200个物种，其中超过1300种分布在北美洲。

寄生蝇的外观极之多样。成虫可以像丽蝇般色彩鲜艳，或是像家蝇般色彩单调。寄生蝇是有最多刚毛及较为粗壮的。牠们的触角有三节，小盾板底明显胀起，触角芒无毛。腋瓣一般都非常的大。第四翅脉向外弯曲。

寄生蝇的分类有很多问题。现时大部份都是基于成虫的形态特征，但也有根据繁殖习性及未成熟阶段来分类的。

The Tachinidae are a large and variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. Over 1300 species have been described in North America alone. Insects in this family commonly are called tachina flies or simply tachinids. As far as is known, they all are Protelean parasitoids, or occasionally parasites, of Arthropoda.