Infestation of live human or other vertebrate host with fly larvae belonging to the insects of order Diptera is called as Myiasis. Infection happens to be by accidental ingestion of eggs or larvae of flies contaminated in food. Myiasis was either found to be asymptomatic or show gastrointestinal symptoms when ingested through food. Human myiasis can present as cutaneous myiasis, anal myiasis, genitor-urinary myiasis, nasopharyngeal myiasis, ocular myiasis, body cavity myiasis, wound myiasis, aural myiasis and intestinal myiasis. Myiasis caused by fly larvae has been classified in to three types including obligatory myiasis, facultative myiasis and accidental myiasis. Fly larvae that require living tissue to survive are responsible for obligatory myiasis, those that infest on wounded or necrosing tissue cause facultative myiasis and those fly larvae that are accidentally ingested or deposited on tissues of human or animals may be responsible for accidental myiasis. Fly larvae belonging to the families Calliphoridae (blowflies), Rhinoestrus spp. (botflies), Gasterophilus spp., Hypoderma spp., Chrysoma spp. and Sarcophagidae (flesh flies) are frequently responsible for myiasis in both pet and domestic animals and humans. Other fly larvae belonging to Anisopodidae, piophilidae, Stratiomyidae and syrphidae occasionally cause myiasis. Depending on the relationship between the host and the infesting fly larvae species, myiasis can be of specific, semi specific or accidental. Flies that need a host for larval development cause specific myiasis Dermatobia hominis (human botfly), Cordylobia anthropophagi (tumbu fly), Oestrus ovis (sheep botfly), Hypoderma bovis (cattle botflies or ox warbles), Gasterophilus spp. (horse botfly), Cochliomyia hominivorax (new world screwworm fly), Chrysomya bezziana (old world screwworm fly), Auchmeromyia senegalensis (Congo floor maggot) and Cuterebra spp. (rodent and rabbit botfly).