Bombylius major
In 3 days ~10% in a week ~20%
Bombylius major (commonly named the large bee-fly, the dark-edged bee-fly or the greater bee fly) is a parasitic bee mimic fly. B. major is the most common type of fly within the Bombylius genus. The fly derives its name from its close resemblance to bumblebees and is often mistaken for them.
Bombylius major exhibits a unique flight behavior known as "yawing" and plays a role in general pollination, without preference of flower types. The fly does not bite, sting, or spread disease. However, the fly uses this mimicry of bumblebees to its own advantage, allowing close access to host solitary bee and wasp nests in order to deposit its eggs. After hatching, the larvae find their way into the nests to parasitically feed on the grubs.
Bombylius major is part of the family Bombyliidae, with a reported 6000 species worldwide. The subfamily Bombyliinae contains approximately 1100 identified species. The genus Bombylius currently comprises around 450 described species.
Bombylius major can be found from April to June throughout temperate Europe, North America and some parts of Asia, concentrated in the northern hemisphere. The species occurs across a variety of environments... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Shenandoah National Park | 🇺🇸 United States | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 3 | Congaree National Park | 🇺🇸 United States | |
| 4 | Great Smoky Mountains National Park | 🇺🇸 United States | |
| 5 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 6 | Acadia National Park | 🇺🇸 United States | |
| 7 | Pyrénées National Park | 🇫🇷 France | |
| 8 | Cévennes National Park | 🇫🇷 France | |
| 9 | Olympic National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Birmingham | 🇬🇧 United Kingdom | |
| 2 | London | 🇬🇧 United Kingdom | |
| 3 | Copenhagen | 🇩🇰 Denmark | |
| 4 | Sapporo | 🇯🇵 Japan | |
| 5 | Liverpool | 🇬🇧 United Kingdom | |
| 6 | Essen | 🇩🇪 Germany | |
| 7 | Prague | 🇨🇿 Czechia | |
| 8 | Paris | 🇫🇷 France | |
| 9 | Vienna | 🇦🇹 Austria | |
| 10 | Warsaw | 🇵🇱 Poland |
Rare
Under 5% of wildlife watchers report a Greater Bee Fly sighting in Olympic National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 182nd most-seen of the 207 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.
March and April
In those months about 10% of wildlife watchers report a Greater Bee Fly in Olympic National Park on a given day, against under 5% in May to February, the lowest months.
Between 1 and 4 pm
Across all the parks we cover, that three-hour window holds the most Greater Bee Fly sightings with a recorded time, and nearly all of them come between 6 am and 6 pm: it is a daytime animal.
9th of 9
Of the 9 parks where we can rate Greater Bee Fly sightings, Olympic National Park ranks 9th at under 5%. The best odds are in Shenandoah National Park (United States, about 10%), Bavarian Forest National Park (Germany, about 10%) and Congaree National Park (United States, about 10%).
Same order: Diptera
The closest relatives of the Greater Bee Fly that you can see in Olympic National Park (order Diptera, Flies) are Common Drone Fly (about 10%), Western Pond Fly (about 10%) and Black-Margined Flower Fly (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Greater Bee Fly is recorded against all the insects logged in Olympic National Park (5 verified sightings from 2019 to 2026), 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.
