Subimago of Leptophlebia marginata Mayflies are hemimetabolous they have "incomplete metamorphosis ". They are unique among insects in that they moult one more time after acquiring functional wings;  this last-but-one winged alate instar usually lives a very short time and is known as a subimago, or to fly fishermen as a dun. Mayflies at the subimago stage are a favourite food of many fish, and many fishing flies are modelled to resemble them. The subimago stage does not survive for long, rarely for more than 24 hours.
This is characteristic of many types of worm infections. Migrating larvae[ edit ] As larval stages travel through the body, they may cause visceral damage, peritonitis and inflammation , enlargement of the liver or spleen , and an inflammation of the lungs. Pulmonary manifestations take place during larval migration and may present as Loeffler's syndrome , a transient respiratory illness associated with blood eosinophilia and pulmonary infiltrates with radiographic shadowing. More than A. The worms had caused torsion and gangrene of the ileum , which was interpreted as the cause of death. However they can rarely cause bowel perforations by inducing volvulus and closed loop obstruction.