Spilomyia sayi
In 3 days ~10% in a week ~30%
Spilomyia sayi (Goot, 1964), the Four-lined Hornet Fly, is a fairly common species of syrphid fly. This species is found from western Canada to northeastern North America. Hoverflies get their names from the ability to remain nearly motionless while in flight. The adults are also known as flower flies for they are commonly found around and on flowers, from which they get both energy-giving nectar and protein-rich pollen. The larvae are known as the short-tailed larvae, suited for moist areas such as rot holes of trees. It is a wasp mimic.
Adults are seen from June to October in the northern part of their range. Males engage in hilltopping, where they find high ground to await females. Larvae are found in decaying heartwood of deciduous trees. For terms see Morphology of Diptera.
Size 10–16 mm (0.4–0.6 in) Head The vertex is black against a black background. In the female the antennal prominece is yellow The face profile is nearly straight, yellow with a wide median black stripe. The antennae are elongate as long as the face is deep. The yellow arista is bare. The antennae are reddish brown to brownish black. The flagellum is moderately elongated. The pedicle... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Acadia National Park | 🇺🇸 United States |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Toronto | 🇨🇦 Canada | |
| 2 | Minneapolis [Saint Paul] | 🇺🇸 United States | |
| 3 | Montreal | 🇨🇦 Canada | |
| 4 | Edmonton | 🇨🇦 Canada |
With luck
About 10% of wildlife watchers report a Four-Lined Hornet Fly sighting in Toronto on a given day, based on 127 verified sightings from GBIF citizen-science data. It is the 181st most-seen of the 1689 insects we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
August and September
In those months about 10% of wildlife watchers report a Four-Lined Hornet Fly in Toronto on a given day, against under 5% in October to July, the lowest months.
Between 10 am and 1 pm
Across all the parks we cover, that three-hour window holds the most Four-Lined Hornet Fly sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 4 cities where we can rate Four-Lined Hornet Fly sightings, Toronto has the highest daily chance: about 10%. Next come Minneapolis [Saint Paul] (United States, under 5%) and Montreal (Canada, under 5%).
GBIF citizen-science records
It is estimated from how often the Four-Lined Hornet Fly is recorded against all the insects logged in Toronto (127 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.
