Ultrastructure of the Immature Stages of Musca domestica (Diptera: Muscidae: Muscinae).

Musca domestica (Linnaeus, 1758) is a muscoid species that is widespread throughout the world and acts as a mechanical vector of different enteropathogens primarily in underdeveloped countries. The adult and its immature forms are associated with decaying organic matter and can be seen visiting human corpses and animal carcass, and the larvae can also cause an infestation on human and animal wounds, feeding on the tissues. These characteristics make them have a forensic significance and, mainly, a great sanitary importance. This study aimed to analyze and describe morphological aspects of their immature stages of M. domestica, including the eggs, the first-, second-, and third-instar larvae, and the puparium using scanning electron microscopy (SEM). The eggs have standard format that all muscoid flies shared. The exochorion has some modified cells that were used for embryonic respiration. The first-instar larvae present two openings on the posterior spiracle as in the second-instar larvae, but with the last one, we can observe the anterior spiracle structure. The third-instar larvae, as in some other Muscidae species, have a posterior spiracular opening with a sinuous form that is located near the edge of the spiracular plate. The puparium morphology is equal to the third instar with a respiratory structure that helps the breathing during the metamorphosis process. This article supports the need for knowledge over the morphological characteristics of the immature forms of the muscoid Diptera (Linnaeus, 1758) at the same time helping with the correct identification of this insect phase.