A tree in your backyard can be a great companion all year round. During the summer it provides you with shade, while during the fall it dazzles you as its leaves turn to beautiful, vibrant orange, red and yellow colors. However, you may have noticed at certain times of year that the leaves of your tree are curling up, turning yellow prematurely, and falling off. You may also notice blisters forming on the leaves and twigs. You might also notice unsightly scars on the branches of your tree, which seem to be attracting unwanted attention from ants and wasps. If you’ve noticed any of these problems occurring with your tree, you may have an invasion of parasites.
There are several types of parasitic insects that can attack your tree. Among the most common are the scale insect, of which there are over 1,000 different species in North America alone. These pests don’t look like bugs crawling around on your tree, instead simply resembling bumps sitting on the branches. They don’t move much and have a strange shape due to their shell coverings, but they can do a great deal of damage to a tree. These insects lay eggs underneath the protective armor that they form over themselves; after a few weeks, the eggs will hatch and the young insects pierce the branches of the tree and begin to drink the sap, slowly damaging the tree and leaving it looking weak and unhealthy. If these insects are not controlled, they are capable of killing the tree.
Another common parasitic insect that may infest your tree is the mite. Parasitic mites are extremely small, so you are unlikely to see them crawling around, however the damage they do can be on a very large scale. The mites tend to form very large groups underneath the leaves of trees, where they inject their pincers into the leaves and feed, damaging the cells of the tree in the process. A certain species called the Spider mite is so named because of the protective silk webs they spin, much like a spider, which you can see across the leaves of your tree. Whatever the species, mites are capable of doing a great deal of harm to your tree as they cause the leaves to yellow and fall off prematurely, weakening the growth of the tree.
Another pest species that causes a great deal of harm in western North America is the mountain pine beetle. These beetles, which are about the size of a grain of rice, burrow under the bark of a tree and lay their eggs there. Normally, trees defend themselves from this type of attack using their natural pitch, so the beetles introduce a fungus that prevents the flow of pitch. This fungus also has the side effect of preventing water and nutrients from being transported by the tree. After the infestation has gone on for some time, the needles will begin to turn red and eventually the tree will die. These beetles have done a great deal of harm to commercial pine trees along the West Coast of the United States. In the past, the cold winters killed off the beetles and prevented their populations from increasing too much, however recent warmer winters have allowed the beetle populations to boom.
So how do you protect your tree from all of these different types of pests? The solution depends on a number of things including the type of pest and the type of tree you have. Often, pests like mites thrive in a dirty, dusty environment, so you can take a lot of steps to curb their spread by simply hosing off the area around your tree every once in a while. Also take steps to regularly inspect your tree, keeping an eye out for any signs of an infestation in the leaves, bark and branches of your tree. These preventative measures will go along way towards preserving the health of your tree.
Another effective solution is to apply dormant oil to your tree. It’s not a pesticide, and so it will not harm birds or beneficial insects, which can also help to control pests naturally. Dormant oil is so called because it should be applied while the tree is dormant – but not during freezing weather, when it could harm the tree bark – and it’s made from petroleum products or cottonseed oil. It kills harmful insects by blocking the apertures they breathe through and disrupting their metabolisms. It is effective not only on adult insects, but on eggs and larvae as well.
To use dormant oil, simply spray it on the leaves and branches of the tree during the winter months. The best time to do this is on a sunny day that isn’t windy, after the leaves have fallen off your tree and before the new ones have grown in.
Ultimately, controlling pests on your trees may require the services of a professional. A tree service, which specializes in removing pests as well as dead or dying tree limbs, can inspect your tree for signs of harmful insects. If they discover any signs of infestation, they can take steps to control the pests.