Sirex woodwasp adult male
David R. Lance, USDA APHIS PPQ, Bugwood.org
Sirex woodwasp is native to Europe, Asia, and northern Africa. It has been the most common species of exotic woodwasp detected at U.S. ports-of-entry associated with solid wood packing materials. Recent detections outside of port areas have raised concerns because this insect has the potential to cause significant mortality of pines.
Keywords: Hymenoptera, solid wood packing materials, pine mortality, toxic mucus, symbiotic fungus, Amylostereum areolatum, resin beads, discolored foliage
|Distribution Map||Distribution Source Image|
Woodwasps are large, robust insects, usually 1-1 ½ in. long. More than a dozen native species occur in North America. Adult Sirex woodwasps have features distinguishing them from native species, including a dark metallic blue or black body, reddish-yellow legs, black feet (tarsi), and entirely black antennae. The abdomen in males is black at the base and tail end with orange middle segments. While native woodwasps attack only dead and dying trees, Sirex woodwasp can attack living pines. At low populations, Sirex woodwasp selects suppressed, stressed, and injured trees for egg laying. Females drill their ovipositors into the outer sapwood to inject a symbiotic fungus (Amylostereum areolatum), toxic mucus, and eggs. Together, the fungus and mucus kill the tree and create a suitable environment for larval development. As adults emerge, they chew round exit holes that vary from 1/8-3/8 in. in diameter. Infested trees may have resin beads or dribbles at the egg laying sites, which are more common at the mid-bole level. Foliage of infested trees initially wilts, and then changes from dark green to light green, to yellow, and finally to red, during the 3-6 months following attack.