Melanostoma scalare
In 3 days ~10% in a week ~20%
Melanostoma scalare, the chequered hoverfly, is a very common species of hoverfly. The European Melanostoma species are not well understood at present. Van der Goot is the most certain identification work. The male genitalia of M. scalare are figured by Dusek and Laska (1967). Other, more accessible, works are listed below.
This species is present in most of Europe, the Near East, North Africa, and the eastern parts of the Afrotropical realm south to Zimbabwe and throughout the Indomalayan realm to New Guinea. Melanostoma scalare can reach a length of 7–10 mm (0.28–0.39 in). These hoverflies have a shining black thorax. The males are longer and slimmer than the females. Also, the male's abdomen is much thinner than that of the female. Further, the yellow markings of the male are roundish or diamond-shaped, while those of the female are triangular patches.
Little is known of its biology, but it is suspected to be general predator of small insects in leaf litter. Adults fly from April to November and inhabit gardens, meadows, and flowering bushes where they feed. The larvae are aphidiphagous. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cairngorms National Park | 🇬🇧 United Kingdom | |
| 2 | Snowdonia National Park | 🇬🇧 United Kingdom |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Birmingham | 🇬🇧 United Kingdom | |
| 2 | Liverpool | 🇬🇧 United Kingdom | |
| 3 | Manchester | 🇬🇧 United Kingdom | |
| 4 | London | 🇬🇧 United Kingdom | |
| 5 | Leeds | 🇬🇧 United Kingdom | |
| 6 | Copenhagen | 🇩🇰 Denmark | |
| 7 | Dublin | 🇮🇪 Ireland | |
| 8 | Brussels | 🇧🇪 Belgium | |
| 9 | Hamburg | 🇩🇪 Germany | |
| 10 | Rotterdam [The Hague] | 🇳🇱 Netherlands |
Rare
Under 5% of wildlife watchers report a Ladder-Backed Hover Fly sighting in Porto on a given day, based on 5 verified sightings from GBIF citizen-science data. It is the 457th most-seen of the 498 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.
April–May and December
In those months about 10% of wildlife watchers report a Ladder-Backed Hover Fly in Porto on a given day, against under 5% in January–March and June–November, the lowest months.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Ladder-Backed Hover Fly sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
15th of 17
Of the 17 cities where we can rate Ladder-Backed Hover Fly sightings, Porto ranks 15th at under 5%. The best odds are in Birmingham (United Kingdom, about 20%), Liverpool (United Kingdom, about 10%) and Manchester (United Kingdom, about 10%).
Same family: Syrphidae
The closest relatives of the Ladder-Backed Hover Fly that you can see in Porto (family Syrphidae, Hover Flies) are Marmalade Hover Fly (about 10%), Stripe-Eyed Lagoon Fly (about 10%) and Common Drone Fly (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Ladder-Backed Hover Fly is recorded against all the insects logged in Porto (5 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.
