Secondary-colonizer
Guides
Dryocoetes betulae
birch bark beetle
Dryocoetes betulae is a bark beetle in the weevil family Curculionidae, commonly known as the birch bark beetle. It is a secondary colonizer that specializes in weakened, dying, or dead birch trees rather than attacking healthy hosts. The species has been documented in paper birch forests of northern Idaho and across North America from Alberta to Newfoundland.
Ips perturbatus
Northern Spruce Engraver
Ips perturbatus, the northern spruce engraver, is a bark beetle in the family Curculionidae (subfamily Scolytinae) that colonizes spruce trees (Picea spp.) across northern North America. It is primarily associated with white spruce (Picea glauca) and typically breeds on trees already killed or weakened by other agents, though it can attack stressed living trees. The species has one generation per year in most of its range, with adults overwintering in the ground. Males initiate galleries and attract 1–4 females to form harems; females construct egg tunnels averaging 10 cm in length and lay approximately 49 eggs each. The species is notable for its associations with ophiostomatoid fungi, particularly Leptographium fruticetum, which may play a role in its ecology.