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Purpuricenus Budensis on the Debegió Hill

Publication date: 2018.07.31

Those who visited Debegió Hill this Spring and early Summer could almost feel the relief of the landscape. After the removal of the large proportion of the invasive acacia, celtis and ailanthus species, the area regained its former shape: closed and open sandland grass, only ornamented by some deliberately preserved domestic aspen trees.

The cherry on top of the experience of the refreshing sight is that the purpuricenus budensis, one of Hungary’s most beautiful bugs can be sighted here.  

It’s a real Mediterranean species: being common in the Balkans and in Spain, it’s categorized as Least Concern in the International Union for Conservation of Nature’s Red List, however, with the remark that in the middle (Northern) parts of its native areas, their number is declining and the species is more endangered. The Northern boundaries of its area run through Slovakia and the Czech Republic. In Hungary, it is a protected species, with a conservation value of HUF 5000.

In the last few decades, the number of purpuricenus budensis individuals seems to have declined in Hungary. Its original habitats are the forest edges of warm-climate oaks and tans and oaks, along with karst bush forests, where its larvae grow for 2-3 years in dead trunks and branches exposed to sunlight. Concerning the host plant, the beetle is not very picky – at least some foreign sources say so, as no larvae have been identified yet in Hungary. Lately, it can be sighted around towns with gardens and parks, as the branches of old fruit- and ornamental trees provide good shelter and food for larvae. A According to the available site-data, it has been sighted in the Eastern and South Eastern part of Pest county the most. Out of the sites specified in the Natura 2000 of the Life + project “Conservation of Dry Grasslands in Central Hungary”, it was sighted in the Debegió Hill and the Fót Somlyó, at the latter site by Csaba Szinetár in 2014.

Mature purpuricenus budensis individuals visit flowers, where they eat the petals, stamen and pistils, but only in a minimal amount; during the short time period they are in an imago state, they live off of the nutrients they gathered when they were larvae. Most probably, the flowers only serve as a meeting point for mating. These red and black beetles are active on the scorching sun, they won’t hide, and won’t escape when disturbed; it’s almost certain that they produce a poisonous or bad-tasting substance, using their contrasted appearance as a warning for predators.

I spotted Purpuricenus budensis individuals on the Debegió Hill in early July 2016 and 2018. On both occasions, they were sitting on the flowers of centaurea or cirsium arvense species.

Purpuricenus budensis individuals can only be confused with one domestic species: the purpuricenus kaehleri. This latter is also a black and red beetle, but the black patch of its both wings doesn’t reach the tip of the wing covers (that of the purpuricenus budensis does reach it) Their lifestyle is quite different: the purpuricenus kaehleri sticks to warm-climate oaks more, and it stays in the foliage, including when its a full-fledged imago. They don’t visit flowers, which makes it hard to spot them. This may be the reason this beetle was considered a rarity (and the higher amount of its conservation value of HUF 10,000.00) However, if we set traps with wine and bananas as a bait in the foliage, their presence is easy to prove (purpuricenus budensis never falls for these). To the extent that by today, purpuricenus kaehleri is considered to be more common than purpuricenus budensis.

Ottó Merkl