Hemlock woolly adelgid: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It covers hemlock woolly adelgid, Adelges tsugae, a small sap-feeding insect of hemlock. Each section names the page it comes from; all were read on October 8, 2026. The parent page, insect pests of trees, compares it with the other pests on the list.

Names

The Canadian Food Inspection Agency, called CFIA, and Natural Resources Canada, called NRCan, both use hemlock woolly adelgid and the scientific name Adelges tsugae Annand. NRCan lists the synonyms Adelges funitecta and Chermes tsugae, and gives the French name puceron lanigere de la pruche. It describes adelgids as small, soft-bodied insects related to aphids, with adults under 2 millimetres.

What the agencies say to look for

The Canadian Food Inspection Agency's hemlock woolly adelgid page (modified August 26, 2025) says the egg sacs look like cotton balls or clumps of snow and sit at the base of needles. Its list of signs that may indicate the insect is white woolly sacs on young twigs, most obvious in spring, premature bud and shoot dieback, premature needle loss, a thinner greyish-green crown, twig and branch dieback and discoloured foliage. It gives tree death within 4 to 15 years. NRCan's scientific fact sheet (revision 2025) says the symptoms of feeding are more evident than the insect: desiccation, discolouration and loss of needles, and deformed shoots near the feeding site. Penn State Extension's hemlock woolly adelgid article (updated June 24, 2026) says the cottony masses normally persist through the season and into the one after, even after the insects are dead, and that overwintering females are black, oval and about 2 mm long.

Hosts

NRCan says the introduced insect completes its life on eastern hemlock and Carolina hemlock in eastern North America, and that western hemlock and mountain hemlock host the insect in western North America. It says the insect has little impact on hemlock species in its native range in eastern Asia. CFIA's list of regulated items names hemlock, yeddo spruce and tiger-tail spruce.

Life cycle as the sources state it

NRCan says the introduced population in eastern North America has two asexual generations a year. The first generation hatches from eggs in June, settles and rests through summer, and resumes development in October. The second generation lays eggs from April through May, and its crawlers settle near the base of needles. Penn State Extension describes overwintering females laying eggs from late winter into June, with crawlers hatching in April to late June and nymphs maturing by late September.

Where it is reported

Source	Where it says the insect is
NRCan	Eastern North America from Tennessee north to Maine and Ontario, west to Michigan and east to Nova Scotia; also western North America. It says an introduced population reached Virginia from Japan, likely in the 1920s.
Penn State Extension	Recorded as a pest in Oregon, California, Virginia, Delaware, Maryland, New York, Pennsylvania, New Jersey, Connecticut, Rhode Island, West Virginia, North Carolina, South Carolina, Georgia, Maine, Vermont, New Hampshire, Tennessee and Kentucky.
CFIA	Regulated areas in British Columbia, Nova Scotia and Ontario, listed below. Its list of detections includes Nova Scotia detections dated 2025 and 2026.

Regulated status in Canada

The Canadian Food Inspection Agency's regulated areas page lists these areas: the entire province of British Columbia; the entire counties of Kings, Lunenburg, Digby, Queens, Shelburne, Yarmouth and Annapolis in Nova Scotia; and in Ontario the Regional Municipality of Niagara, Haldimand County, the City of Hamilton and the Township of Alnwick/Haldimand. It says a Movement Prohibition Notice applies to a property where the insect is found, and bars affected materials from leaving it. The program is set out in directive D-07-05. NRCan says government agencies in both the United States and Canada regulate the insect, defining regulated areas and restricting the movement of foliage, nursery stock and firewood from infested areas. No United States order page was read for this profile.

What the agencies say about moving wood

The CFIA page lists the items that cannot be moved out of a regulated area without approval: plants for planting of hemlock, yeddo spruce and tiger-tail spruce, forest products with bark attached such as logs, lumber, bark chips and wood mulch, dried branches, Christmas trees, fresh decorative wreaths, foliage and branches, and firewood of all species. It says people who need to move regulated material can contact their local CFIA office. It says the insect can spread by wind, animals and the human movement of nursery stock, logs and other wood products. Wider rules are in the guide on moving wood and firewood.

Who takes a report

CFIA asks anyone who sees signs in hemlock trees to report suspected sightings immediately, through its online report form. The contact pages for each country are on reporting a tree pest in Canada and in the United States.

Management as the agencies list it

NRCan says a biological control program with predatory beetles and flies has existed in the United States since 1992, that foliar insecticides can reduce populations on small nursery trees but are not practical for large trees or forests, and that systemic products injected or sprayed on the trunk are widely used in the United States. It adds that some hemlock stands show partial resistance and are used in breeding programs, and that only a licensed professional can apply pesticides in some jurisdictions. Penn State Extension describes soil injection by commercial applicators around large trees. This page gives no product names, rates or timings. For who may apply, see pesticide licences.