Invasive Woodwasp, Sirex noctilio: A Potential Pest of Pines in Arkansas

Sirex noctilio, the Sirex woodwasp, is native to Europe, Asia, and northern Africa. This insect was first found in North America in 2004, and current populations are confined to northeastern North America. Adult males are black with an orange stripe, while females are a dark blue. Both sexes have yellowish wings, and range from ½ - 1 ½” long. Eggs are laid in the tree’s xylem tissue, and larvae bore holes in the wood while feeding on fungus provided by the adult. Larvae can spend up to two years inside the tree. The Sirex woodwasp attacks conifers, especially scots, jack, loblolly, shortleaf, and slash pines. Resin dripping down the stem of a tree is one of the first signs of infestation, as are round (~¼”) exit holes. The Sirex woodwasp is not expanding its range quickly in North America, and it has yet to reach the southeastern U.S. Maintaining healthy basal area levels in your pine stands is an effective management tactic.