Psychoda alternata
In 3 days ~10% in a week ~20%
Psychoda alternata is a species of moth fly in the family Psychodidae, commonly known as the trickling filter fly or drain fly. The larva is semiaquatic and lives in the gelatinous ooze associated with leaks of sewage effluent, drains, and in trickling filter systems.
The adult female fly is about 4 mm (0.2 in) long, the male being slightly smaller. The wings are broad and held at an angle away from the body. They are clad with dense tufts of hairlike scales along the veins, and are grey, with a mottled appearance. The wing muscles are relatively weak and the insects mostly run or hop, occasionally making short flights. The males hatch first and only survive for a few days, while unmated females may live for a week.
Originating in North America, this insect has spread around the world. Its range includes Europe, western Asia and South America. It had become established in Britain by 2000, in Brazil by 2006, in Norway by 2011, in Iraq and Croatia by 2013 and in Spain by 2016. The larvae develop in moist areas rich in organic matter such as drains and trickling filter systems, but also in ditches and sludges of decaying organic matter.... Wikipedia →
| # | Park | Country | Daily sighting probability |
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More parks will be added in future updates.
Rare
Under 5% of wildlife watchers report a Trickling Filter Fly sighting in Dallas on a given day, based on 12 verified sightings from GBIF citizen-science data. It is the 873rd most-seen of the 1412 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 20%, if each day is a fresh chance.
Any time of year
In every month with enough records, under 5% of wildlife watchers report a Trickling Filter Fly in Dallas on a given day, so our monthly data shows no clear season.
Among the best
Of the 3 cities where we can rate Trickling Filter Fly sightings, Dallas ranks 2nd at under 5%, level with the leaders once rounded. The best odds are in Austin (United States, under 5%).
GBIF citizen-science records
It is estimated from how often the Trickling Filter Fly is recorded against all the insects logged in Dallas (12 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
