Canadian Forest Service Publications

Detection of hemlock woolly adelgid (Hemiptera: Adelgidae) infestations with sticky traps. 2015. Fidgen, J.; Whitmore, M.; Turgeon, J. Great Lakes Entomologist 48(3-4):125-131.

Year: 2015

Available from: Great Lakes Forestry Centre

Catalog ID: 36442

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.

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We deployed sticky traps underneath the crown of eastern hemlock, Tsuga canadensis (L.) Carrière, to assess their sensitivity at detecting crawlers (1st instar nymphs) of the non-native hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). We found these traps more sensitive at detecting infested trees with low densities of A. tsugae than branch-tip sampling with pole pruners. We observed two peaks of crawler abundance at all sites: these peaks likely represented the timing of the progrediens and sistens crawler stages of A. tsugae. Deployment of sticky traps in treated and high-risk stands may prove useful at detecting residual and new infestations, respectively.

Plain Language Summary

The hemlock woolly adelgid (HWA) is a devastating non-native insect pest of eastern and Carolina hemlock in eastern North America. We used sticky traps underneath the crown of eastern hemlock to capture crawlers (1st instar nymphs) of HWA. This passive form of crawler sampling reflected the seasonal abundance of crawlers and was more effective at detecting infestations of HWA compared to a pole pruning technique. Crawler sampling makes possible the indirect sampling of the entire live crown (habitat of HWA) of hemlock whereas conventional techniques such as visual survey and pole pruning can only reach the lower third of the crown of mature trees. Crawler sampling could be used in treated areas to determine if residual HWA populations remain and also to delineate around newly discovered infestations.

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