Influence of diameter of a sampling device on detectability of wool of the hemlock woolly adelgid (Hemiptera: Adelgidae) in the canopy of eastern hemlock (Pinaceae)

Abstract Ball sampling is an active technique of sampling the upper canopy of hemlock, Tsuga sp. (Pinaceae), to detect the nonnative hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). We tested a 7.5-cm-diameter wooden ball fitted with Velcro ® with a BigShot ® slingshot that sends the ball into the upper hemlock canopy. The 7.5-cm ball detected wool with fewer sampling attempts per tree and had a higher detection rate after 10 sampling attempts than a 5-cm wooden ball using a much smaller HyperDog ® slingshot did. However, sampling with the 7.5-cm ball took 20% longer per tree and fatigued shooters after only 30–40 shots due to the size and effort required to use the larger slingshot. A larger sampling device (= greater Velcro ® surface area) significantly improved detection of adelgid wool and is recommended, provided a more efficient launching system is developed.