Poplar borer (Saperda calcarata Say) is a native North American wood boring beetle that attack native aspen, balsam poplar and willows. Poplar borer beetle also attack a variety of poplar cultivars including Swedish aspen and Towering Poplar. It is one of the most common insect for Swedish aspen and Towering poplar in urban area. Many Swedish aspen and Towering poplar trees have been planted in urban areas that besides their short life span, susceptibility to drought and bronze leaves disease (BLD) are also frequently attacked by this insect. These fast-growing trees are planted along property fences, roads, driveways, on limited spaces and anywhere to create a “ living wall” for private screens to separate their properties from others. Like other tree species these aspen/poplars are susceptible to many insects and diseases.
It is relatively easy to recognize this insect. From a short distance, you will notice the long antennas on the round head with a gray colour body that is sparkled with small brown spots on wings and several orange stripes along the elongated body. A mature insect is 2-3 cm in length with antennas that are the same size as the body. The life cycle of this tree is between 2 to 5 years. The insect attacks all age of poplar trees but prefers trees that have more than 10 cm in diameter, a size of stem or branch. They usually attack from the south to south-west side of tree. They prefer healthy and vigorous trees, but the heaviest attack on drought-stricken trees will occur.
The poplar borer usually does not kill a tree but it weakens it. Larvae is creating a tunnel in heartwood, therefore weakening the structure of the stem. With a heavy infestation, some trees will break down due to strong wind, snow, or ice at weak spots. High population of this insect can reduce growth, attract a variety of fungus that will further deteriorate the decay of the stem. Woodpeckers eating larvae will further enlarge holes and speed up the decay of the wood. It rarely kills trees
There are several symptoms to recognize that trees are under the attack of this insect:
- Wet orange/brown colour oozing sap with a fine frass at an entrance hole is the best way to recognize the symptom of this insect
- Sawdust on the ground close to the trunk is another significant symptom
- Swollen bark area shows signs of larvae in the tree
Poplar borer is wood boring beetle that is difficult to control. There are several management options for the control of the poplar borer:
- Avoid planting too many Swedish aspen and Towering poplar on your property. There are several other columnar tree species that you can plant with a much longer life span and a better resistance to insects and diseases
- If you have a one tree with a heavy infestation – remove it and burn it
- Many native insect predators and enemies of this insect will keep this species in checks, but you must encourage the diversity of trees and shrubs species in your property
- There are a very few chemical and biological products to successfully control this insect
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