Dytiscus marginalis
In 3 days ~10% in a week ~30%
The great diving beetle (Dytiscus marginalis) is an aquatic diving beetle native to Europe and northern Asia, and in the UK is common in Wales, much of England and southern Scotland but less common on chalk and in the far north.
The great diving beetle, true to its name, is a rather large insect. The larvae can grow up to 60 millimetres (2.4 in) in length, while the adults are generally 27–35 millimetres (1.1–1.4 in). These beetles live in fresh water, either still or slow-running, and seem to prefer water with vegetation. They are dark-coloured (brown or green to black) on their back and wing cases (elytra) and yellow on their abdomen and legs. The male's wing cases are shiny, while those of the female are finely grooved. A voracious predator, this beetle hunts a wide variety of prey including small fish. The first two pairs of legs of the male are equipped with numerous suction cups, enabling them to obtain a secure grip while mating, and on their prey.
They are able fliers, and fly usually at night. They use the reflection of moonlight to locate new water sources. This location method can sometimes cause them to land on wet roads or other hard wet surfaces. Before they dive, they collect air bubbles in their wing cases which goes through the spiracles. The jaws of a great diving beetle are strong compared to their body size.
The beetle reproduces by laying eggs under water in the mesophyll of an aquatic plant leaf. The incubation period is between 17 and 19 days. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Wadden Sea National Park | 🇩🇪 Germany | |
| 2 | Pyrénées National Park | 🇫🇷 France |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Birmingham | 🇬🇧 United Kingdom | |
| 2 | Nizhny Novgorod | 🇷🇺 Russia | |
| 3 | London | 🇬🇧 United Kingdom | |
| 4 | Moscow | 🇷🇺 Russia |
Rare
Under 5% of wildlife watchers report a Great Diving Beetle sighting in Wadden Sea National Park on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 422nd most-seen of the 818 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.
March, May, July and November
In those months about 10% of wildlife watchers report a Great Diving Beetle in Wadden Sea National Park on a given day, against under 5% in April, June, August–October and December–February, the lowest months.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Great Diving Beetle sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Yes
Of the 2 parks where we can rate Great Diving Beetle sightings, Wadden Sea National Park has the highest daily chance: under 5%. Next come Pyrénées National Park (France, under 5%).
GBIF citizen-science records
It is estimated from how often the Great Diving Beetle is recorded against all the insects logged in Wadden Sea National Park (10 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.
