Bug FAQAlkali Fly
Cirrula hians · Order: Diptera · Family: Ephydridae
Also called: Mono Lake Alkali Fly
Alkali flies are tiny dark-brown insects about 4 to 7 mm long, with a metallic greenish-blue thorax and smoky brown wings. They live in the shallow, tufa-rich waters of the benthic-littoral zone, especially around Mono Lake in California. The species is native to the northwestern United States and also occurs in Canada and Mexico.
Source: Wikipedia
How to recognize it
Adults have a dark brown body, a thorax that shines metallic greenish or bluish, and smoky brown wings.
Source: Wikipedia
Size
The adult body length ranges from about 4 to 7 mm (0.16 to 0.28 in).
Source: Wikipedia
Where it lives
They prefer the benthic-littoral zone with abundant tufa, a porous limestone deposit. Mono Lake in California hosts a large population of this species.
Source: Wikipedia
What it eats
Larvae swim underwater and feed on algae and bacteria. Adult flies can walk on or under water, also feeding on algae.
Source: Wikipedia
Life cycle
In summer, adults live 3 to 5 days, feeding and laying eggs just below the water surface. The eggs develop underwater, with the emerging adults obtaining oxygen from algal photosynthesis.
Source: Wikipedia
When you see it
Their activity, feeding, and egg-laying occur throughout the summertime.
Source: Wikipedia
Where it is found in the US
Recorded in 5 of 51 states and DC. Most records: California, Utah, Nevada, Washington, New Mexico.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What do alkali fly larvae eat?
The larvae feed on algae and bacteria while swimming underwater.
Source: Wikipedia
Where are alkali flies commonly found?
They are common in the northwestern United States, Canada, Mexico, and especially in tufa-rich shallow waters like Mono Lake, California.
Source: Wikipedia
How long do adult alkali flies live?
Adults live for about three to five days during the summer.
Source: Wikipedia
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Ephydra_hians
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-25 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-25.