What are Aphids?
Aphids are tiny soft-bodied, pear shaped insects that are found clustered together on the leaves and needles of trees and shrubs. Aphids will attack a wide variety of tree and shrub species. The insects are commonly found on ash, aspen, apple, linden, certain conifer species, and many other ornamental trees and shrubs. Some aphids spend their entire life on one plant while others go from plant to plant. An aphid population can also increase in numbers very quickly.
What are signs of Aphid damage?
There are a few different signs to identify if you have aphid activity in your trees or shrubs. The leaves of the the tree may appear to be curled, thickened, or discolored. The damage occurs when the aphid sucks the sap and plant juices out of the tree leaf or needle. Because the aphids are unable to fully digest all of the sugars of the plant sap it will excrete the excess in a liquid form called “honeydew”. This residue will drop onto leaves, branches, tree trunks, cars, and patios leaving a distinct shiny look. A sooty mold may also develop on the honeydew and cause those surfaces to appear dirty. Ants will feed on this honeydew and are often present where aphids are actively feeding.
Aphids need to be controlled at the first sign of an attack. There are many natural predators of the aphids that include lady bugs, green lacewigs, and other parasitic wasps. When large populations of aphids are present and natural predators cannot mitigate the insect, insecticides may need to be implemented. In most cases, depending on the location of the attack, a foliar spray is most effective. Repeat applications may be necessary as re-infestation can occur. In certain cases the trees may also be systemically injected to control a present generation of aphids or to provide season long control against the insect. The micro-injection is very timing specific and should be performed at leaf emergence up until leaves are fully mature.