Hymenoptera: Siricidae: Sirex noctilio Fabricius

An invasive, European wood wasp was detected in North America in Oswago New York in the fall of 2004. Additional surveys in 2005 detected the wasp several miles from the initial discovery. This wasp has caused significant damage to various pine tree species in Australia, New Zealand, South Africa, and Brazil, where it was introduced. In North America, it has been detected in Scotch, red, and white pine, but is known to infest Austrian, Monterey, loblolly, slash, shortleaf, ponderosa, lodgepole, and jack pine. Female wasps select stressed host trees to lay eggs in, and also deposit a pathogenetic fungus, Amylostereum areolatum, which kills the tree making it a more suitable host for the larva. Fortunately there are natural enemies that attack this wasp, including native ichneuminid wasps. In other countries, a nematode, Bedingia siricidicola, has provided effective suppression of this pest. Efforts are underway to study the efficacy, environmental impact, and potential for use of the nematode in North America.

Sirex noctilio is extremely difficult to distinguish from native wood wasps, but some signs and symptoms can be helpful in determining if the pest is present. Look for wilting needles, which turn downward, and eventually turn red or brown. Egg laying causes the tree to produce resin flow or beading. When adults emerge from trees, they exit through grouped, large, round holes. Occasionally, females will die when laying eggs, and remain stuck in the tree.

The DCNR Bureau of Forestry participates in a multi-agency effort to detect and control this invasive threat to Pennsylvania pine trees. Other cooperating members of the task force include USDA/APHIS, USFS, and the PA Department of Agriculture. In 2005, the Bureau of Forestry assisted this effort by trapping for Sirex noctilio in three Northern Pennsylvania counties, using Lindgren funnel traps. No Sirex noctilio were detected in Bureau traps or in any of the 23 traps placed by cooperating agencies.

In 2006 efforts were greatly expanded as we continued to cooperate with other federal and state agencies, to detect this pest. A surveillance grid was established within a 150-mile radius of the original New York detection site. A total of 275 traps were placed in this area, and an additional 36 traps were placed outside the gridded area. On July 26, 2006, a single female specimen was collected from a trap at Hills Creek State Park in Tioga County. See the original press release by visiting this link: http://www.agriculture.state.pa.us/agriculture/cwp/view.asp?A=390&Q=140787. Six trees were felled in the immediate vicinity and will be examined for signs of establishment in 2007. A second female was collected in Orwell Township in Bradford County on August 10, 2006. In addition to trapping, several visual surveys were conducted for Sirex noctilio in 2006, all of which were negative. Please see the December 2006 issue of FPM News for additional information.

To report possible infested trees in Pennsylvania, contact:
The Pennsylvania Department of Agriculture 1-866-253-7189, or
The Department of Conservation and Natural Resources, Bureau of Forestry,
Division of Forest Pest Management (717) 948-3941.

Return to Invasive Threats Home