This insect kills pine forests
The European wood wasp (Sirex noctilio) arrived in the United States most likely inside crating and associated cargo shipping materials. It has been found in New York state. In its native range it is a minor pest but in countries where it has been accidentally introduced, it has become a serious pest of many species of pines.
European wood wasps attack living pine trees although they prefer stressed trees. Female wasps insert eggs into the tree trunk and at the same time inject a symbiotic fungus and toxic mucus which act together to kill the tree. The immature wasps develop inside the tree and feed on the fungus as they tunnel through the wood. Foliage on an infested tree wilts and changes from dark green to light green to yellow and finally to red. Pines of all varieties including ornamentals can be attacked.
Image Right: European wood wasp
Robert Dzwonkowski, www.forestryimages.org
How to identify European wood wasps
- Wood wasps (a.k.a. horntails) have a spear-shaped spine at their “tail end” which no doubt contributed to their common name. Female also has a stout ovipositor for inserting eggs into wood.
- They are large, robust insects about 1 to 1 1/2 inches long; they do not have a constricted “waist” behind their wings like other wasps.
- Adults are metallic bluish-black; males have an orange band around the abdomen.
- Their legs are reddish-yellow; their feet are black.
- Wood wasps have black antennae.
- Round exit holes about 1/8 to 3/8 inch diameter in the trunk or pine trees mark where adults emerged (usually in July through September).
- Native wood wasps, cicada killer and potter wasps could be confused with the European wood wasp.
What you can do
It is unlikely that European wood wasps have reached Missouri. However, they can hitch rides on firewood and nursery stock so it pays to keep a watchful eye. If you think you’ve found European wood wasps in Missouri, collect a sample by trapping the insect in a zippered plastic bag. Place the bag in the freezer for several days to kill the insect then mail the sample in a sturdy container (35mm film canisters or empty pill bottles work well) to one of the addresses below. Be sure to include your contact information and the date and location where you captured the sample.
Forest Entomologist, Missouri Department of Conservation
1110 S. College Ave.
Columbia, MO 65201
State Entomologist, Missouri Department of Agriculture
P.O. Box 630, 1616 Missouri Blvd.
Jefferson City, MO 65102