Polygraphus poligraphus

This pest attacks primarily juvenile or mid-aged spruces with thinner bark (trunk thickness of ca. 20 cm). The stems  are usually heavily infested in full length. In case of outbreak the pest causes dieback of individual trees or entire groups. Characteristic for its galleries is an irregular layout of larval tunnels with pupation chambers bored deeper in the sapwood. The nuptial chamber is not visible when the phloem layer is examined. The first generation occurs in May and its second generation swarms in July. In warmer areas there may even partially occur a third generation. Preferring especially forest stands affected by pollution or other agents. Pest’s outbreak usually occurs in hills and mountains.