Rhantus suturalis
In 3 days ~10% in a week ~30%
Rhantus suturalis, commonly known as the supertramp beetle or cosmopolitan diving beetle, is a species of diving beetle (Dytiscidae) with a cosmopolitan distribution. Adult Rhantus suturalis range from 10.5 to 13.0 mm in length. The head is black with a pale anterior margin and a pale marking between the eyes, and the antennae and palps are also pale. The pronotum is pale with a usually well-defined dark mark in the middle. The elytra are pale brown and covered in fine punctures. The sternites of the abdomen are completely black. The legs are brown and often have the metatibiae and metatarsi darker. Males differ from females in the basal tarsomeres of the prolegs and midlegs being weakly dilated, and the protarsal claws being unequal and much shorter than the terminal tarsomere.
In Europe, R. suturalis coexists with the also-common species R. exsoletus, but that species has a vague black posterior margin to the pronotum instead of a central dark mark, and its abdominal sternites are yellow instead of black. In Australia, the only other Rhantus species is R. simulans, which is larger (12.8-13.5 mm) and only found in the country's southwest, unlike the more widespread... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Egmont National Park | 🇳🇿 New Zealand | |
| 2 | Great Otway National Park | 🇦🇺 Australia |
Rare
Under 5% of wildlife watchers report a Cosmopolitan Diving Beetle sighting in Great Otway National Park on a given day, based on 5 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 369th most-seen of the 418 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.
July and December–February
In those months about 10% of wildlife watchers report a Cosmopolitan Diving Beetle in Great Otway National Park on a given day, against under 5% in March–June and August–November, the lowest months.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Cosmopolitan Diving Beetle sightings with a recorded time, and about half of them come between 6 pm and 6 am: it is most active around dawn and dusk.
2nd of 2
Of the 2 parks where we can rate Cosmopolitan Diving Beetle sightings, Great Otway National Park ranks 2nd at under 5%. The best odds are in Egmont National Park (New Zealand, about 10%).
Same order: Coleoptera
The closest relatives of the Cosmopolitan Diving Beetle that you can see in Great Otway National Park (order Coleoptera, Beetles) are Variegated Lady Beetle (about 20%), Large Spotted Ladybird (about 10%) and Small Transverse Ladybird Beetle (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Cosmopolitan Diving Beetle is recorded against all the insects logged in Great Otway 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.
