Blackheaded budworm

Acleris gloverana

The blackheaded budworm is one of the most destructive defoliators in coastal B.C. Population levels periodically reach outbreak levels at 10 to 15-year intervals and outbreaks have been recorded since the 1930s. 

On this page

• Description
• Host species
• Life cycle
• Damage symptoms
• Identification images

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Description 

Larvae have black or brown heads, their bodies are greenish in colour and they're up to 18mm long.

Host tree species

The western blackheaded budworm prefers to feed on the upper crowns of dominant and codominant trees.

Western hemlock and true firs are the preferred hosts but Engelmann spruce, white spruce and Douglas-fir can also be fed upon. All ages are susceptible.

Life cycle

Larvae pupate in August, on the branches of host trees, and they emerge as adults in late August or early September.

Damage symptoms

Trees can be completely defoliated from a heavy attack, and severe defoliation can result in growth reduction and susceptibility to other biotic or abiotic forest health factors. 

Trees can die when they experience successive years of severe defoliation. Defoliation is visible in the summer and from a distance the defoliated trees will have a reddish-brown hue. 

Other defoliators such as the western spruce budworm cause similar damage.

Identification images