 They develop into adults that reside in body cavities, most commonly the peritoneal cavity or pleural cavity, but also occasionally in the pericardium ("M. perstans"), subcutaneous tissue ("M. ozzardi") or dermis ("M. steptocerca").In "M. perstans", size range for female worms is 70 to 80 mm long and 120 μm in diameter, and the males measure approximately 45 mm by 60 μm.In "M. steptocerca", the females measure approximately 27 mm long.