3 Insects That Can Damage The Western Hemlock Tree

The western hemlock tree is a beautiful evergreen conifer that offers a slightly different look to the traditional, more popular conifers. The hemlock still has the dark green needles associated with conifers, and the brownish cones, but the undersides of the needles have a distinct white hue that can make the hemlock a beautiful shade tree for your yard.

Keep your hemlock free of pests by monitoring for signs of an insect infestation. Here are a few of the common insects that can target the tree, what to look for, and how a tree care service can help.

Hemlock Looper

The hemlock looper is a highly-destructive defoliating insect that can potentially kill your hemlock tree. Adult loopers are modest-sized brown moths, and the females lay small eggs throughout the hemlock tree in the fall months. The eggs hatch in spring and the emerging larvae are what can potentially destroy your tree.

Looper larvae are caterpillars that have yellowish, hairless bodies with dark markings. The larvae feed on the tree's needles and travel in a looping pattern, thus the name, eating everything in their wake and dropping partially eaten and dying needles to the ground. A strong infestation can completely defoliate your hemlock tree and strip the tree of much-needed nutrients.

Call a tree care service as soon as you spot partially eaten needles collecting around the base of your tree. The service can use pheromone traps, insecticides, or both to help treat your looper infestation and potentially save your tree from a full defoliation – and possibly even tree death. 

Hemlock Sawfly

The hemlock sawfly lays small, yellowish eggs in the bark of the hemlock tree. These eggs hatch, and blackish-green, striped larvae emerge. The larvae feed on older foliage on the hemlock tree but will move on to the healthier, newer foliage when they grow larger and stronger. Eventually, the sawfly larvae can defoliate significant parts of the tree, with the crown showing the earliest signs of bald spots.

Harsh winter weather can often kill off the sawfly infestation, but it's not guaranteed. If you try to let the problem fix itself, you do run the risk of the sawflies surviving for another year of infestation and defoliation. You should call a tree care service to try and control the sawfly problem now, with a combination of manual removal and insecticides.

You might also want a tree trimming service to prune away any branches severely affected by the defoliation process. This can help control the sawfly population and make your tree look healthier overall. 

Hemlock Woolly Adelgid

Hemlock woolly adelgids are tiny, aphid-like insects that create a wool-like substance as they lay eggs within the hemlock tree. All the adelgids are females due to asexual reproduction, which can cause the infestation to spread out of hand quickly. The laid eggs hatch into larvae that feed on younger bark tissue, such as that on smaller twigs. As the larvae age and grow, the feeding intensifies and moves onto the thicker wood such as the branches and the heartwood of the trunk. If larvae cause substantial damage to the heartwood, the hemlock tree will die, and you will need a tree removal service.

If you notice a woolly material on your tree and signs of healthy twigs dropping to the ground, call in a tree care service as soon as possible. The adelgid problem is controllable with carefully tailored and applied chemical controls.


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