The hemlock woolly adelgid, or HWA, is one of the most destructive insects that has inhabited North America. HWA is a destructive pest that threatens the eastern hemlock and the Carolina hemlock. These insects are known for destroying large portions of healthy thick forests and continue to become more of a nuisance every year. The HWA come from Japan and were first sighted in North America in the early 1950s.
Signs of Hemlock Woolly Adelgid
The HWA is causing widespread mortality of hemlock trees. The HWA feeds by sucking sap from the hemlock and spruce trees. Trees that have been invaded by the HWA are usually a gray greenish color, rather than the deep green trees in the forest should be. One sure sign that an HWA is present is the sight of their very recognizable egg sacs.
The HWA egg sac resembles small balls or clouds of cotton that cling to the underside of hemlock branches. The HWA is able to produce two additional generations per year, making it difficult to completely remove them and giving them capability to destroy more and more hemlock trees every year. The HWA can lay between one hundred and three hundred eggs beneath the hemlock branches.
Poison Injecting Toxin of the Hemlock Woolly Adelgid Facts
After sucking the sap from the hemlock tree, the HWA may also inject a type of poison or toxin into the tree while they are eating. This toxin will cause the tree to lose needles and make it impossible to produce new growth. After an HWA infestation, trees usually only last an additional four to ten years after infestation. If there are trees that happen to survive, they are still weakened and do not live as long as they would have.
Predator Release Hypothesis
One way that forests are being protected from the HWA is the release of black lady beetles. These beetles are specific to only eating the HWA and do not harm the vegetation that is in the forest. The beetle was discovered feeding on the HWA back in 1992 in Japan. Since 1995 the bureau of forestry has released over one hundred thousand adult beetles into forests that are infected with HWA.
New research and testing is currently being done concerning the release of imported silver flies. Researchers find an adelgid infested hemlock branch, and then cover it with a mesh bag that’s filled with silver flies. This way the silver flies have no other food sources and the researches can go back to look at the branch with a microscope and see how many HWA the flies have eaten.
Professional Pest Control Management
If you notice any signs of the HWA in your trees on your property or near your home, like the egg sacs that resemble a cottony cloud, call a professional pest control company to assist you eliminating the HWA and protecting your vegetation form their harmful effects.