Question
This is our 20th summer in our current home.  We have a Maple tree 2 1/2 stories high in front of our home.  It provides shade for the entire front yard and extends over our driveway as well as any street parking.  This is the first year we found sap glistening all over our vehicles.  Our cars our sticky and the residue attracts dirt.  We have been forced to wash our cars every weekend and by then they look embarrisingly dirty.  Why is our tree doing this now? We understand the tree has aphids. Is this going to be an on going event or is it something to do just with this year. Can we spray the tree for the aphids. If it were up to my husband he would chop it down, it's definately a pain in the you know what. We have a one car garage so our other cars are at a disadvantage.
Any help you could give would be greatly appreciated.


Answer
Yes this sounds like aphids. Aphids are small (1/16-1/8 inch long), soft bodied insects commonly called plant lice or ant cows. Virtually every plant has at least one aphid species that attacks it. These small insects are masters of reproduction and are often found in great numbers on stems or leaves. Some species even feed on the roots of plants. They range in color from green to brown, red, black or purple. Some species may even have different color forms in the same colony. Most have the soft exoskeleton exposed, but some species produce waxy, cottony strands which cover the body. These are often called woolly aphids.

Aphids are identified by their sucking mouthparts, long, thin legs, long antennae, and a pear-shaped body. Aphids may be winged or wingless and colonies often have both forms.

Aphids excrete a sugary liquid called honeydew. This honeydew drips onto plant foliage or other structures and provides a suitable place for black sooty molds to grow. Ants often tend or care for aphids in return for the honeydew. Therefore, if ants are running over a plant, look carefully for aphids.

Each plant reacts differently to aphid attacks. Some plants show no response to the aphids, while other plants produce distorted (twisted, curled or swollen) leaves or stems. Occasionally, aphids may actually kill leaves or small shoots. Since aphids may move from one plant to another, they may transmit plant diseases which contaminate the sucking mouthparts.

Probably the most common disturbance caused by aphids is their never-ending production of honeydew. This sweet liquid drips onto plant foliage and stems and is soon covered with black sooty mold. Cars, sidewalks, and lawn furniture under trees with aphids are also covered with this sticky fluid. Ants, flies and wasps appreciate the sugary meal and can become a nuisance of their own. Even though plants may look bad from the growth of sooty molds, these fungi do not damage the plant tissues. Once the aphids disappear, the sooty mold often dries up and falls off the plant.

There are several insecticides that can be sprayed on the foliage to kill the aphids but on large trees it is difficult to get the spray up into the crown and cover all leaves. Another insecticide that can be used is called Bayer Advanced Tree and Shrub Insect Control Concentrate. This is applied to the soil around the tree and the roots transport the insecticide to the leaves and stems and when the aphids suck the plant juices the insects are killed. Check with your local nursery for this product.

Here is a web link to the Bayer product if you want more information on this product.

http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html