Observations on the Morphology and Life History of Herpetomonas muscae-domesticae in North American Muscoid Flies

Abstract

Certain flagellate parasites of insects are of particular interest to investigators because of both their general biological importance and the relationships which they bear to mammalian parasites belonging to the genera Leishmania and Trypanosoma. Perhaps the commonest and most extensively investigated of all these insect flagellates is Herpetomonas muscae-domesticae, a parasite of the common muscoid flies. No attempt will be made to give an extensive review of the work of previous investigators, since it would make this contribution unnecessarily lengthy. The references at the end of this paper, particularly those of Wenyon (1913) and Brug (1914), should be consulted for publications referred to in this paper and not listed in the bibliography. The writer has encountered three distinct morphological types of Herpetomonas in the muscoid flies of North America (Text fig. A). (1.) The type that is unmistakably the Herpetomonas muscae-domesticae which Prowazek (1904) described, whose distinctive features are strongly staining flagella, each flagellum thickened at the margin of the cell body so as to form marginal granules, and a large deeply staining parabasal body. This flagellate is almost always found in a state of division, making it appear biflagellated. During the summer of 1922 this species was found to be present in varying percentage's in the alimentary canal of Phormia regina, Lucilia sericata, Calliphora erythrocephala, Cochliomyia (Chrysomyia) macellaria, Musca domestica and Sarcophaga bullata. The Herpetomonas found in these six species of flies were morphologically indistinguishable, and exhibited no more morphological variations in hosts of different species than in different hosts of the same species. In a later paper will appear a report on cross-infection experiments which seems to indicate that H. muscaedomesticae is the common parasite of these six species of flies. (2.) In Muscina stabulans, Calliphora erythrocephala, and Limosina sp. is a herpetomonad of somewhat smaller size with a flagellum and parabasal body less strongly developed than in H. muscae-domesticae.