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Tips for Fighting a Spruce Weevil Insect Infestation

closeup of spruce weevil insect

Do the evergreen trees in your yard seem to be stunted or deformed? You may be fighting a spruce weevil infestation. Here’s what you need to know about this pest.

What Are Spruce Weevils?

Spruce weevils, also known as white pine weevils, are harmful pest beetles belonging to the Curculionidae family. They commonly appear in spruce and pine ecosystems throughout Canada but can wreak havoc on trees in residential and commercial areas.

What Damage Does a Spruce Weevil Cause?

Spruce weevils feed on shoots and needles of pine and spruce trees. They cause significant damage around the very top of the tree — the portion called the terminal leader — decimating the top two to four years of growth. This permanently stunts the tree’s growth. Repeated infestations can also cause severe stem deformation and forked trunks. Spruce weevils are a particularly serious problem for Christmas tree growers.

Signs Your Tree Has Spruce Weevils

One of the most noticeable signs of a white pine weevil infestation is damage to the current year’s terminal leader. The leader becomes wilted and droopy, forming a characteristic shepherd’s crook shape. The needles on the affected stem turn yellowish-green, then reddish-brown and eventually fall off.

This damage typically appears in mid-June or early July. However, the first sign of attack is the appearance of droplets of resin oozing from tiny feeding holes in the leader stem early in the spring.

How to Manage and Treat a Spruce Weevil Infestation

Managing and treating a spruce weevil infestation requires a combination of preventive measures and targeted interventions.

To prevent infestations, it’s crucial to maintain the overall health of the tree by providing proper nutrition, adequate water and regular pruning. Trees that are stressed or damaged are more susceptible to infestation by the white pine weevil. Growing evergreen trees under a canopy of 50% shade can make the leader shoots less attractive to the weevils.

Pruning infested terminal shoots at the first signs of infestation can help minimize the spread of spruce weevils.

Severe infestations may need to be treated with pesticides. Currently, dimethoate is the only product registered to control the white pine weevil. It’s registered for use on Sitka spruce trees only and must be applied by a certified professional like the arborists at ArborCare®. In addition, the product cannot be applied in residential areas, including parks, schools and playgrounds. Dimethoate must be applied at the time of egg laying, generally in early May.

Tree Care Specialists in Calgary

If you think the trees in your yard are suffering from spruce weevil damage, the expert arborists at ArborCare can help. We offer consultation and assessment services to help you analyze the health of your trees and determine the best course of action. We offer complete tree care services including stump grinding, tree pruning, removal and planting. Contact us today for more information about our services.

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