Hexagenia bilineata
In 3 days ~10% in a week ~20%
Hexagenia bilineata is a species of mayfly in the family Ephemeridae. It is native to North America where it is found in the Upper Mississippi Valley. Sometimes adults of this mayfly are so abundant as to cause a nuisance because of their enormous numbers. The larvae are aquatic and burrow in mud and the adult insects have brief lives.
When the adults are ready to emerge, the mayfly nymphs (larvae) swim to the surface of the water during the night. Their skin splits and winged subimagos struggle free, usually in less than a minute, and fly to nearby trees to rest. They are a dull gray color and have short, coarse legs, bristly cerci and cloudy, grayish wings. Some eight to eighteen hours later, these subimagos moult into mature adults (imagos). These are altogether more delicate in appearance than the subimagos; the wings are transparent, the legs are longer and more slender, the cerci lack bristles, the eyes are larger and the body is patterned in brown and cream. The females are much larger than the males.
Hexagenia bilineata occurs in the Upper Mississippi Valley. Adults appear in summer and are found near still and slow-moving water... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Montreal | 🇨🇦 Canada |
Rare
Under 5% of wildlife watchers report an Emergent Mayfly sighting in Montreal on a given day, based on 7 verified sightings from GBIF citizen-science data. It is the 694th most-seen of the 926 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 an Emergent Mayfly in Montreal on a given day, so our monthly data shows no clear season.
Only Montreal, in our data
Montreal is the only city on Wallace's Line with enough records to rate Emergent Mayfly sightings: under 5% of wildlife watchers there report one on a given day.
GBIF citizen-science records
It is estimated from how often the Emergent Mayfly is recorded against all the insects logged in Montreal (7 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.
