Methods to Monitor European Woodwasp in Colorado
Figure 3. Lindgren funnel similar to those used to monitor for European woodwasp. Photo courtesy of Kenneth Gibson USDA-FS
Currently there is no specific attractant or pheromone lure available for the European wood wasp and early detections were found in sites monitoring for exotic bark beetles. Current monitoring projects directed at the European woodwasp use Lindgren funnels with a lure (Figure 3). Lures for monitoring have involved alpha:beta pinene (70:30), alpha pinene alone, or a three component lure containing cis-verbenol, ipsdienol and methyl butenol. One disadvantage of all these lures is that the effective attraction range is only about 50 yards. Also, these lures are not specific to the European woodwasp and are attractive to several native Sirex species as well as many other wood boring insects.
Identification of captured insects is also a problem as the species require very detailed examination by experts. However suspect Sirex species of woodwasps associated with pines should be immediately brought to the attention of a Colorado State Extension office or sent directly to Colorado State University.
Identification of the European Woodwasp
Adult European woodwasps are cylindrical-bodied stingless wasps approximately 1-1.5 inches long. They can be easily separated from other wasps as they lack the constricted “waist” behind their wings. Adults of the European wood wasp are generally metallic blue to black; males have a conspicuous orange band around the middle segments of the abdomen (Figure 4). Most have reddish-yellow legs, black feet (tarsi), and entirely black antennae. However, there is some variation in these features.
Figure 4. European woodwasp adult (male). Photo courtesy of David Lance
As with all woodwasps, there are differences in size and appearance between the sexes. Females tend to be slightly larger than males but are best distinguished by a long, stout spine at the end of the body (Figure 2 and 5). This is the ovipositor, used to insert eggs under the bark of trees. Males have only a short blunt spine at the end of the body.
Larvae of the European woodwasp are a creamy white and reach a length of around one inch when full-grown (final instar). All larvae are legless and have a distinctive dark spine at the rear of the abdomen. However, these features are shared by all the other native species of horntail larvae that presently occur in Colorado. Currently no keys to identify woodwasp larvae to the species level have been developed nor is this likely because of physical similarities. Methods based on genetic markers may ultimately be useful for separating larvae. Figure 5. European woodwasp adult (female). Photo courtesy of David Lance