Paragus haemorrhous
In 3 days ~20% in a week ~40%
Paragus haemorrhous, the black-backed grass skimmer is a common widespread species of hoverfly found in many parts of Europe, Africa and the Nearctic. Hoverflies can remain nearly motionless in flight. The adults are also known as flower flies for they are commonly found on flowers from which they get both energy-giving nectar and protein-rich pollen. The larvae are predators on aphids.
For terminology Speight key to genera and glossary external link to inaturalist images Size 4.3–5.9 mm (0.17–0.23 in) Head The face is yellow, moderately projecting, with a black median stripe in both sexes. The third antennal joint is sordid reddish below. The eyes are uniformly pilose."
Thorax The scutellum entirely black. Abdomen Segment 1 is black and well-developed. Segment 2 is black or has a posterior margin that is red. Segments 3 through 5 are usually entirely red-orange to dark red in males. The superior lobe varies in shape and size, with an apex that is nearly truncate to strongly oblique, and with a length from one to two times that of the surstylus.
Wings The wings are hyaline with a brownish grey stigma. Legs The legs are yellow and light brownish yellow. The basal... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Addo Elephant National Park | 🇿🇦 South Africa | |
| 2 | Shenandoah National Park | 🇺🇸 United States | |
| 3 | Great Smoky Mountains National Park | 🇺🇸 United States | |
| 4 | Table Mountain National Park | 🇿🇦 South Africa |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Sacramento | 🇺🇸 United States | |
| 2 | San Diego | 🇺🇸 United States | |
| 3 | San Francisco | 🇺🇸 United States | |
| 4 | Los Angeles | 🇺🇸 United States | |
| 5 | Salt Lake City | 🇺🇸 United States | |
| 6 | Baltimore | 🇺🇸 United States | |
| 7 | Cape Town | 🇿🇦 South Africa | |
| 8 | Portland | 🇺🇸 United States | |
| 9 | Washington | 🇺🇸 United States | |
| 10 | Seattle | 🇺🇸 United States |
With luck
About 10% of wildlife watchers report a Common Grass Skimmer sighting in San Francisco on a given day, based on 351 verified sightings from GBIF citizen-science data. It is the 65th most-seen of the 737 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
May to September
In those months about 10% of wildlife watchers report a Common Grass Skimmer in San Francisco on a given day, against under 5% in October to April, the lowest months. Those are among San Francisco's driest months, with almost no rain against 110 mm in December.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Common Grass Skimmer sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 12 cities where we can rate Common Grass Skimmer sightings, San Francisco ranks 3rd at about 10%, level with the leaders once rounded. The best odds are in Sacramento (United States, about 10%) and San Diego (United States, about 10%).
Same family: Syrphidae
The closest relatives of the Common Grass Skimmer that you can see in San Francisco (family Syrphidae, Hover Flies) are Oblique Streaktail (about 10%), Eurasian Drone Fly (about 10%) and Thick-Legged Hover Fly (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Common Grass Skimmer is recorded against all the insects logged in San Francisco (351 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.
