a longhorn beetle and one of the largest beetles in Sweden, growing up to three centimetres long. This very rare nocturnal beetle lays eggs and lives inside dead, sunlit fallen Baltic pine trees. There are very few dead trees in the forest today. As a result Tragosoma depsarium has declined dramatically, and is now on the Red List as Threatened – Vulnerable. With the right action, it is possible to create habitats for the beetle to find its way back, thrive and spread.
Burns create the right habitat
Conservation burns, like those Holmen has been carrying out in Berga for over 20 years, create a sparse forest with a lot of dead wood, which is exactly what Tragosoma depsarium needs. Beetles have hatched in these burned areas every year since 2015. The centimetre-wide holes which the beetles leave in the fallen pines are easy to spot, but it is rare to see a fully developed Tragosoma depsarium. In autumn 2022, a living specimen was finally caught in one of Holmen’s insect traps.
Other special conservation species in Berga
Happily, Holmen’s nature conservation efforts have also made Berga Knowledge Forest an ideal habitat for another five special conservation species. Four of them are the fly Hormopeza obliterata Zetterstedt, which lives primarily in burned forests; the beetle Calitys scabra, which is dependent on older dead pine wood; and two species of horned powder-post beetle: Stephanopachys linearis and Stephanopachys substriatus. The latter lives in recently dead coniferous trees with dry bark or in fire scars, just at the border between living and dead bark. As recently as 2022, another beetle species was also found: Aradus signaticornis.