Sirex Woodwasp
The Sirex woodwasp (Sirex noctilio) is native to Europe, Asia, and northern Africa. Adults lay eggs 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.
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.
To identify a Sirex woodwasp infestation, look for the following signs:
- Resin Dripping: One of the earliest indicators is resin oozing down the tree's stem, often caused by the woodwasp's egg-laying activity.
- Exit Holes: Round exit holes, approximately ¼ inch in diameter, can be seen on the tree's surface where adult wasps emerge.
- Tree Decline: Infested trees may show signs of wilting, yellowing needles, or overall decline due to the larvae feeding on the tree's xylem tissue.
- Larval Tunnels: Inside the wood, larvae create extensive tunnels while feeding, often accompanied by the presence of a symbiotic fungus introduced by the adult wasp.
These signs are most commonly observed in conifers such as Scots, jack, loblolly, shortleaf, and slash pines.
This Sirex woodwasp was first found in North America in 2004, and current populations are confined to northeastern North America. The insect 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.
