Exocentrus stierlini, an interesting species occuring in Central/Eastern Europe, Russia, Kazakhstan and Mongolia, has been described from Central Europe by Ludwig Ganglbauer in 1883 [✮]. E. stierlini is ecologically associated with willows (Salix purpurea and Salix cinerea). Beetles fly from June through August. They infest thin shoots 6 - 30 mm diameter of viable and decaying willow trees. Larvae hatching from eggs bore into bark of twig and later in wood, leaving small inlet on surface, and plug it with fine frass. Longitudinal galleries are usually made in upper layer of wood (in this case, undamaged wood up to 0.1 mm thick remains between gallery and bark), more rarely to a depth up to 5 cm. Length of gallery in wood up to 9.5 cm or more, width 2.0 - 2.5 mm. Galleries sometimes enter deeper into wood, sometimes approach shoot surface. Before pupation, larvae) make pupal cells in the upper wood layer longitudinal to the shoot with an exit almost up to the bark. Length of cell 7 - 12 mm, width 3.5 - 4.0 mm [❖]. Biology of this rare and not often collected species was in detail described in works of Jacek Hilszczański et al. [✳] and Jacek Kurzawa with Jerzy M. Gutowski published in 2021 [✧].

Body length:	4 - 6 mm
Life cycle:	1-2 years
Adults in:	June - August
Host plant:	willows (Salix purpurea and Salix cinerea)
Distribution:	Central and Eastern Europe, Russia, Kazakhstan, Mongolia

The depicted beetles were: (PJ) beaten from thin dead twigs of a willow (Salix sp.) found in Altaı (formerly Zyryanovsk or Зырян/Zyrıan) environs, East Kazakhstan in June 2019 and (JK) reared from larva found in Salix purpurea L. in Biebrza National Park (Podlaskie Voivodeship, Poland) in June 2021.

Collected by Jiří Kadlec and Jacek Kurzawa