Larval dipterans may develop in the subcutaneous tissues of the skin or organs of many domestic animals, producing a condition known as myiasis. There are two types of myiases based on degree of host dependence. In facultative myiasis, the fly larvae are usually free-living; however, in certain circumstances, these larvae can adapt themselves to a parasitic dependence on a host. In obligatory myiasis, the fly larvae are completely parasitic, ie, they depend on the host to complete the life cycle. Without the host, obligatory parasites will die.
Last full review/revision August 2013 by Charles M. Hendrix, DVM, PhD