Question
Hi Jim
I have a very large oak tree that has an incredible amount of bees that appear to be feeding.
I live near St. Louis, there seems to be little protrusions near the leaves that they are feeding from.
There are also bumble bees and wasps.
I noticed that there are a few of the leaves that have been
eaten ( Japanese Beetles ? )
The bees don't seem to be swarming or building a nest, but there must be a thousand of them.


Answer
Sounds like the problem is a scale insect. Scale insects are so prolific that they quite often cover twigs and branches. The insect lives under the shell like structure and sucks the plant juices from the twig.


Large numbers of these soft scales may give an infested twig a warty appearance. One of the first indications of an infestation of this pest is the abundance of honeydew (sticky, sugar-rich material) secreted by developing soft scales during the growing season. Ant and wasp populations that seek the honeydew are often found in association with this soft scale insect. These ants may need to be managed since they protect this scale insect from predators and parasitoids. The honeydew is a substrate on which black sooty mold grows. The sooty mold may turn the leaves, twigs, and other surfaces beneath an infestation black. Feeding by this pest may weaken young trees by removing plant fluid. Bees and ants feed on the honeydew.

The scales are difficult to control after the insect has constructed the scale. Systemic insecticides are absorbed and moved within plants. If the plant is infested with a scale species susceptible to systemic insecticide, systemics are particularly useful where it is not practical to spray because plants are large or spray may drift to unintended areas. Depending on the product, systemic insecticide may be applied by spraying foliage, or applying on or into soil beneath trees and shrubs, where the insecticide is absorbed by roots.

There are some newer insecticides that will control the scales that are applied to the soil and the roots transport the insecticide to the branches and leaves and when the scale sucks the juices it kills the insect. Certain persistent insecticides that move systemically in the plant may provide control through the fall. Imidacloprid (Bayer Advanced Garden Tree and Shrub Insect Control) is a newly available systemic insecticide that can provide scale and aphid control on trees for several months following application to the soil.