Callidium violaceum
In 3 days ~10% in a week ~20%
Callidium violaceum, commonly known as the violet tanbark beetle, is a species of beetle in the family Cerambycidae. It was described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. It is a medium-sized (8–16 mm), broad, black longhorn beetle, with wing covers that have a blue-violet metallic sheen, making the species easy to recognize. Callidium aeneum looks similar but has a green metallic sheen. The antennae are about half the length of the body. The pronotum is wider than long, with rounded sides, coarsely punctured, and with fairly long, erect, dark hairs. The wing covers are coarsely and densely punctured, but not wrinkled, with short hairs and a distinct metallic shine. The legs are black, the thighs slightly thickened, otherwise slender.
The larvae develop under the bark of dead spruce and pine. If you use materials with leftover bark as building material, the species can also attack these, and it can live indoors for several generations. It’s also common for it to get into homes with conifer firewood. Since the species can look like the house longhorn beetle (Hylotrupes bajulus), this can cause a lot of concern, but it’s not such a serious pest since the larvae don’t bore deep into the wood. Problems can be avoided if all materials used are thoroughly cleaned of bark. Larval development takes two years. Outdoors the adults are seen in June-July; indoors, they can appear over a longer period.In Norway it seems to be quite uncommon in forests, the most common habitat is stacks of firewood stored under a roof. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Hohe Tauern National Park | 🇦🇹 Austria | |
| 2 | Bavarian Forest National Park | 🇩🇪 Germany | |
| 3 | Wadden Sea National Park | 🇩🇪 Germany |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Copenhagen | 🇩🇰 Denmark | |
| 2 | Vienna | 🇦🇹 Austria | |
| 3 | Prague | 🇨🇿 Czechia | |
| 4 | Berlin | 🇩🇪 Germany | |
| 5 | Moscow | 🇷🇺 Russia |
Rare
Under 5% of wildlife watchers report a Violet Tanbark Beetle sighting in Vienna on a given day, based on 16 verified sightings from GBIF citizen-science data. It is the 666th most-seen of the 1406 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.
May
In that month about 10% of wildlife watchers report a Violet Tanbark Beetle in Vienna on a given day, against under 5% in June to April, the lowest months.
Between 3 and 6 pm
Across all the parks we cover, that three-hour window holds the most Violet Tanbark Beetle sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 5 cities where we can rate Violet Tanbark Beetle sightings, Vienna ranks 2nd at under 5%, level with the leaders once rounded. The best odds are in Copenhagen (Denmark, under 5%).
Same family: Cerambycidae
The closest relatives of the Violet Tanbark Beetle that you can see in Vienna (family Cerambycidae, Longhorn Beetles) are Alpine Longhorn Rosalia (about 10%), Common Grammoptera (about 10%) and Dorcadion aethiops (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Violet Tanbark Beetle is recorded against all the insects logged in Vienna (16 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.
