Oestrus ovis, the sheep ‘nasal bot fly’, somewhat looks like a honey bee, has a rudimentary mouth parts and do not feed. The larva of the sheep nasal fly is responsible for causing a condition in sheep and goat called nasal myiasis, oestriosis or ‘false gid’. The disease occurs when adult fly deposit first larvae (L1) into the nostrils of its host. The larvae develop into L2 and L3 in the nasal cavities and sinuses in due course. Sneezing and nasal discharges are the major clinical signs seen in infected animals. The pathogenic reaction occurs when the larvae irritate the mucosa with their spines and hooks during their development and also due to an allergic reaction induced by molecules excreted/secreted by the larvae. Sometimes damage of the skulls of the bones and injury to the brain occur to such an extent that signs of high-stepping gait and in-coordination suggesting the animal suffers from Coenurus cerebralis infection and hence the infection is also called false gid. Keeping in view the importance of the fly, the morphology, biology, pathogenesis, immunological reaction and various control measures of Oestrus ovis are discussed in this review.