The Alkali fly (Ephydra hians) belongs to the family of shore flies. This is a very diverse family with about 425 species recorded in North America alone. Many of them are very abundant around alkaline lakes. A soda lake or Alkaline lakes or soda lakes are lakes a pH value above 7, typically between 9 – 12, which means they are rather brine than normal freshwater.
An calm summer days swarms of Alkali flies carpet the shoreline of lakes such as Mono Lake in California. Here is a video that gives you an idea how abundant these flies can be at times:
These flies are also food. Most birds prefer dining on the flies. Alkali flies provide more fat and protein than e.g. the brine shrimp that is the main food source for flamingos. The alkali fly was an important source of food for the native Kutzadika'a people during the summer months. Since the pupae are rich in fat and protein, they were an excellent source of food that were dried and used in stews.