Eastern Larch Beetle (ELB)

Impact – Larch / Tamarack are deciduous conifers. Recent reports have found the beetles are attacking and destroying healthy trees which is uncommon as the insects were previously believed to prey on trees that were already compromised. Historical outbreaks of small infestations have been linked to environmental stress making the tree vulnerable to the ELB. The Adirondack Park has the highest concentration of Eastern Larch in NYS. Once a stand is infested there can be substantial mortality over the course of several years.

What it is – The Eastern Larch beetle is a bark beetle native to North America. Their main host is the native Eastern larch tree also called Tamarack. Recent reports of dead and dying Eastern Larch / Tamarack trees in the Adirondacks have been traced to the Eastern Larch beetle. Extended periods of cold winter temperatures can slow the beetle’s growth cycle and keep populations from exploding. Outbreaks may be associated with global warming.

How do identify – Beetles are about 4 mm (5/32 “). Recently, almost all reports of symptomatic trees have been in DEC regions 5 & 6 (Eastern and Western Adirondacks). Signs of ELB infestations include two millimeters (3/32”) bore holes in the trunk and branches, defoliation before the larch’s natural deciduous needle drop in the fall, sap runs not caused by physical damage, bark stripped from the tree by woodpeckers and vertical boring galleries in the phloem.