Keep watch for these tree-attacking insects

Provincial woodlot management specialist offers tips for controlling pests and improving tree health

White pine weevils have been infesting young spruce trees in Alberta.
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When it comes to trees, there are a few different insects to keep an eye out for this year.

“The yellow-headed spruce sawfly has been a problem for spruce the last few years, as well as spider mites,” said provincial woodlot management specialist Toso Bozic.

“White pine weevil has also been a problem for young spruce trees as they target the leader (the top branch). Poplar and willow tree borer has been very dominant, along with a large infestation of forest tent caterpillar in the northern part of the province.

“Sawfly larvae can be removed by hand and squished, whereas mites can be controlled with high-pressure soap water, or by encouraging beneficial insects such as lady beetles. Young willow trees infected by willow borer can be cut to the base of the tree. Regrettably, there is very little that can be done with large aspen trees infected by poplar borer.”

Besides insects and diseases, other factors can potentially contribute to declining or dying trees. This includes improper use of chemicals, salt along roads, age of the trees, soil type, wildlife damage, competition, and heavy grazing.

Bozic recommends only using insecticides as a last-ditch effort to control problems with insects.

“Monitoring is key when it comes to insects,” he said. “From mid-May until Oct. 1, landowners should check their trees weekly to see what is going on. Monitoring also helps them keep on top of which trees may need watering under dry conditions, or may need help with other issues.”

If monitoring turns up insects, disease, or any other issues contributing to tree weakening, Bozic suggests taking a picture and emailing him at [email protected].

“If you can also provide photos from the surrounding area, it’ll help me determine the extent of the problem, as well as if other issues are at hand.”

More resources on insects are available at (The Insects, Diseases, Weeds, and Pests Publications website can be found by searching for ‘pest publications.’)

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