Apple trees and their fruit are prone to insect damage. Controlling infestations does not have to be difficult. By using biological controls, such as predatory insects, you can control many infestations without resorting to harmful chemical sprays. When biological controls fail, chemical solutions are an option.
Flathead Apple Tree Borer
The flathead apple tree borer is an insect that attacks apple trees throughout North America. It is particularly harmful to young trees or trees stressed by drought. Its larvae bore through the bark of an apple tree, and feed on the tree's outer sapwood. Tunnels in the tree can be as long as 3 inches. In the fall, these insects will bore deeper into the wood to winter over. In the spring, the next generation will emerge. To control re-infestations, wrap the trunk from ground level to the lower branches. Use several layers of newspapers or burlap. In some cases, you can dig out the larvae with a knife, but if you do, be sure to seal the wound. If these methods fail, employ the services of a licensed professional to apply insecticides.
The coddling moth grows from larvae that bore into apples. Another name for these moths is "common apple worm." They damage apples in two ways. In some cases, the worm will make a hole in the skin and die before boring into the apple. This type of damage is called a sting. In other cases, the larva bores deep into the apple causing deep entry damage. To control coddling moths, release predatory parasites like Trichogramma platneri, which eat the larva of the coddling moth. Another method is to spray your apple trees with organic controls to disrupt coddling moth mating, such as granulovirus (Cyd-X), spinosad, and kaolin clay.
Rosy Apple Aphids
Rosy apple aphids cause new leaves on apple trees to curl. When they gather on fruit spurs, they can cause the apples to improperly develop. Rosy apple aphids tend to be a problem only for one season before subsiding. The number of rosy apple aphids varies from year to year, and in years of minimal numbers, the aphids are not a serious problem. Rosy apple aphids have a number of natural predators, such as ladybugs, lacewings and soldier beetles, which feed on the aphids and do a good job of controlling these pests. Soap sprays, an organic control, can also help to minimize this pest during years of high infestation.