Lampyris noctiluca
In 3 days ~20% in a week ~50%
Lampyris noctiluca, the common glowworm of Europe (see also "glowworm"), is the type species of beetle in the genus Lampyris and the family Lampyridae. Lampyris noctiluca presents conspicuous sexual dimorphism. The males are winged, with brown elytra, a clearer pronotum and a large brown spot in the middle, while females are larviform, with no wings, and they are often twice the size of the males (up to 25 millimetres (1 in) in length).
These beetles use their bioluminescence to attract mates. The adult females are mostly famed for their glow, although all stages of their life cycle are capable of glowing. In Britain, this species is fairly common, compared to its cousin Phosphaenus hemipterus—the lesser glow worm—which is very rare.
The etymology of Lampyrus is from Greek for "shining ones"; the genus includes species known as fireflies or lightning bugs. Contrary to its name, it is not worm-like, but a beetle. These beetles are typically the most active at night and spend their day under debris, or in the ground. The larvae are also nocturnal and rarely seen, only coming out when the conditions are right in the months of April to October. The adult stage is much shorter than the larvae stage but they are much easier to spot then as they glow for a few hours and only stop glowing after mating. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Białowieża National Park | 🇵🇱 Poland | |
| 2 | Mercantour National Park | 🇫🇷 France | |
| 3 | Cévennes National Park | 🇫🇷 France | |
| 4 | Snowdonia National Park | 🇬🇧 United Kingdom | |
| 5 | Pyrénées National Park | 🇫🇷 France | |
| 6 | Bavarian Forest National Park | 🇩🇪 Germany |
With luck
About 10% of wildlife watchers report a European Glow-Worm sighting in Snowdonia National Park on a given day, based on 9 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 227th most-seen of the 387 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 50%, if each day is a fresh chance.
June
In that month about 20% of wildlife watchers report a European Glow-Worm in Snowdonia National Park on a given day, against under 5% in May, August–September and November–March, the lowest months.
Between 9 pm and midnight
Across all the parks we cover, that three-hour window holds the most European Glow-Worm sightings with a recorded time, and about 6 in 10 of them come between 6 am and 6 pm: it is seen both by day and at night.
Among the best
Of the 6 parks where we can rate European Glow-Worm sightings, Snowdonia National Park ranks 4th at about 10%, level with the leaders once rounded. The best odds are in Białowieża National Park (Poland, about 10%), Mercantour National Park (France, about 10%) and Cévennes National Park (France, about 10%).
Same order: Coleoptera
The closest relatives of the European Glow-Worm that you can see in Snowdonia National Park (order Coleoptera, Beetles) are Woodland Dor Beetle (about 30%), Garden Chafer (about 30%) and Two-Banded Longhorn Beetle (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the European Glow-Worm is recorded against all the insects logged in Snowdonia National Park (9 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.
