Sirex Wood Wasp
  Common
names: Sirex wood wasp, European wood wasp
Scientific name: Sirex noctilio Fabricius
Description: Adult Sirex wood wasps are 1 to 1.5
inches long, lack the narrow ‘waist’ of other groups of wasps,
and have a pointed plate-like projection extending from the tip of the abdomen. Females
are metallic blue-black in color with orange legs. Males are similar
to females, but the middle portion of the abdomen is orange and the hind
legs are black. Larvae, which tunnel in wood, range from 0.04 to 1
inch long and are creamy white with a dark spine projecting from the abdomen.
Impacts: Sirex wood wasps feed primarily on pines,
including jack, eastern white, red, Scots, and Austrian pines. It also
infrequently attacks spruce, larch, fir and Douglas fir. It prefers
stressed trees, but can kill apparently healthy trees. Injury results
from larval feeding and a toxic mucus and fungus injected into the tree when
eggs are laid. Infestations have been documented causing up to 80%
tree mortality.
History: In its native range, spanning from Europe
and northern Africa to Mongolia and southern Russia, the Sirex wood wasp
is generally considered a minor pest. In contrast, this wasp is considered
a major pest in areas it has invaded, such as New Zealand, Australia, South
Africa and South America. It has recently invaded North America where,
as of winter 2006, it was detected in New York, Pennsylvania and Ontario.
Symptoms of attack:
- Trees with needles pointing downward (wilted) and crown turning
light green to yellow to reddish brown
- Beads of resin on bark (oozing from egg-laying sites)
- Round adult
exit holes (0.1 to 0.3 inch diameter)
- Fungal stains (long, narrow
and brown) running with the grain on sapwood
  
If you suspect you have seen this pest
or an infestation in Minnesota:
“Arrest the Pest” Hotline
651-201-6684 (metro)
1-888-545-6684 (toll free)
robert.koch@state.mn.us
Invasive
Species Exclusion Unit
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