Morphology of the infective larval stage of the equid parasite Habronema muscae (Spirurida: Habronematidae), from houseflies (Musca domestica).

The infective larva of the spirurid nematode Habronema muscae, a parasite of houseflies, was measured and specimens fixed in Karnovsky's fluid were examined by scanning electron microscopy. The oral opening contains six teeth and is surrounded by large bilobed dorsal and ventral lips and smaller lateral lips. A pair of amphids lie behind the lateral lips. There are two rows of four cephalic papillae. The body is deeply ridged, both transversely and longitudinally. The caudal end of the worm is studded by small papillae. The position of the anal opening is somewhat ambiguous. These larval morphological features are discussed, as well as the changes which must have occurred in the metamorphosis of the infective larva to the adult in the stomach of horses.