Tethininae, formally the family Tethinidae[2] is a paraphyletic group of tiny drab-coloured or grey Acalyptratae flies.

Workers in dipterology which are unfamiliar with tethinids often associate these flies with the presence of seashores, particularly sandy beaches and coastal lagoons.

This is true for most strictly thalassophilous species, which occur on dunes, sandy soil and wrack heaps stranded on the beach.

However, many entomologists often ignore or simply overlook the fact that populations of certain species also inhabit biotopes situated far off from sea littorals, sometimes several hundreds of kilometres inland, and are almost always closely dependent on the proximity of continental saline environments.

It is well known that most species, if not all, belonging to the subfamily Pelomyiinae are not thalassophilous flies, but are almost exclusively found inland, associated with meadows, mountain passes, forests, areas and waters polluted by rotting waste, industrial emissions or debris of slaughterhouses and poultry farms (sites of salt accumulation and enrichment), as well as desert oases.