Questions and Answers
Hemlock Woolly Adelgid (Adelges tsugae) Detection in Nova Scotia

What is hemlock woolly adelgid?

Hemlock woolly adelgid (HWA) is an aphid-like insect that attacks and kills hemlock trees by feeding on nutrient and water storage cells at the base of needles. HWA can be spread by wind, animals, and human movement of nursery stock, logs, and other wood products.

Where was the initial detection of hemlock woolly adelgid?

The CFIA was first informed of the possible presence of hemlock woolly adelgid in Nova Scotia on July 12, 2017, when a tree removal company contacted the Agency with a suspected find in Weymouth, Digby County, NS. A sample was collected from the site, and on July 18, 2017, the CFIA entomology lab confirmed the sample submitted as positive for HWA. Based on this detection, the CFIA is conducting additional survey work in Southwestern Nova Scotia to determine whether the pest has become established in the area, and if so, the extent of the spread. Any further actions will depend on the results of these additional surveys.

Where else is hemlock woolly adelgid found?

Hemlock woolly adelgid has not previously been detected in Atlantic Canada. In its native range within Asia, hemlock woolly adelgid – Adelges tsugae – population levels are controlled by natural enemies and by host resistance. HWA was first reported in Western Canada (British Columbia) in the 1920s and in the United States (Virginia) in the 1950s. Since its initial discovery, it has been establishing itself along the eastern coast of the United States with findings reported from Maine to Georgia. To date, only two detections of HWA have occurred in Canada since the 1920s – in Ontario; Etobicoke in 2011 and the Niagara Area, in 2013. These populations have since been eradicated, and the region continues to be monitored for new infestations.

How did hemlock woolly adelgid arrive in Southern Nova Scotia?

It is not known at this time how the hemlock woolly adelgid came into Southwestern Nova Scotia, and the exact source will be difficult to determine. Dispersal of HWA occurs by wind, storms, hurricanes, birds, animals, and human movement of nursery stock, logs, and other wood products, including firewood.

Is hemlock woolly adelgid considered a regulated pest?

Yes, import and domestic movement requirements are in place to prevent the introduction and minimize the spread of the hemlock woolly adelgid. To see the complete policy, please refer to the CFIA website: D-07-05 – Phytosanitary requirements to prevent the introduction and spread of the hemlock woolly adelgid (Adelges tsugae Annand) from the United States and within Canada

What is the potential for hemlock woolly adelgid to spread?

Once established, HWA will spread naturally viawind, birds, animals, and human movement of nursery stock, logs, and other wood products, including firewood. To help prevent the spread of this pest the public is encouraged not to move potentially infested firewood and other hemlock forest products.

How is the CFIA managing the detection ofhemlock woolly adelgid?

The CFIA continues to survey for hemlock woolly adelgid in Nova Scotia. Further regulatory measures will be put in place by the CFIA as required after the site assessment.

How does the CFIA manage emerging plant pests in Canada?

If a new plant pest is introduced in Canada, the CFIA works to reduce its impact. A formal pest risk assessment may be conducted to identify its distribution, biology, pathways of spread, environmental and economic impact. If a pest is introduced, the CFIA may also conduct pest surveys to detect, monitor and take action against new populations.

What are the potential economic and ecological impacts of hemlock woolly adelgid?

The economic value of hemlock to the forest industry is not as high as other trees species, however, eastern hemlock can be processed for use in general construction or as pulp. Hemlock woolly adelgid, and the resulting loss of hemlock trees, has the potential to cause major ecological impacts in Canada. In many forests, hemlock serves as a foundation tree in the environment. Loss of eastern hemlock could negatively affect the health of vegetation, birds, aquatic organisms and mammals.

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