2017-11-24

Eastern Blackheaded Budworm

Photo Credit: Natural Resources Canada

Found all across Canada, the eastern blackheaded budworm (Acleris variana, Fern.) is reported all across Canada and itfeeds on 20 different conifer tree species, primarily on the balsam fir, then white spruce and black spruce.

This native moth is very similar in appearance to the spruce budworm moth and outbreaks in the Maritimes before the late 1920's were attributed to the spruce budworm. The first outbreak credited to the eastern blackheaded budworm in Nova Scotia was in 1929. From 1945 to 1950 a series of outbreaks ran through the Maritimes and since then every ten to fifteen years localized outbreaks have been reported in Nova Scotia mainly in maturing stands with a high balsam fir content. 

The larvae feed on the current year's growth, defoliating the trees, which leads to partial or total destruction. If the numbers of larvae are high, feeding on the previous year's foliage will occur. The showing of red foliage is an early symptom of an infestation and can be seen from a distance. Significant tree growth loss and tree mortality is the result of a major outbreak. The adult moths fly from mid-August to early October with the main flights usually ending by mid-September. There is only one generation per year.

If a large population exists, balsam fir of all age classes can be defoliated in a single season and also reduce growth which may cause widespread mortality. The top of more mature trees are usually defoliated first. It is believed that the eastern blackheaded budworm comes before the spruce budworm.

Information was provided by Natural Resources Canada - Canadian Forest Service and partially excerpted from NS DNR.

Web Resources

CFS Impact Note 43

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