Question
This tree is showering our patio with a sticky residue and now little white mite-type bugs seem to be falling out of it, too.  It is a tall tree so can I treat it at ground level and, if so, with what?  Thank you.

Answer
These are an insect called  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 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.

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.

For most aphid problems, particularly those associated with leaf curls, insecticides that move systemically within the leaf or plant provide the best control. The most common systemic insecticide available to homeowners is Orthene (acephate). Cygon (dimethoate) also may be available as a spray for use on evergreens.

Some insecticides can be applied to the soil and taken up by the roots of the plants. These are called systemic insecticides. The most recent, Imidacloprid, is sold under the trade name Bayer Advanced Garden Tree & Shrub Killer Concentrate. (Merit is the trade name of imidacloprid used by professional tree care companies.) It is applied as a drench over the root zone. An older梐nd much more toxic梥oil systemic insecticide that is still available for some ornamental plant uses is DiSyston (disulfoton). DiSyston is sold as granules or in plant food mixtures for soil application.

There are several insecticides effective for aphid control when sprayed on plants. Perhaps most effective are those with systemic activity that allows them to move through the plant. Acephate (Isotox, Orthene) is the most widely available systemic insecticide.