Question
My silver maple tree is loaded (tens of thousands) with tiny insects that resemble a knat with wings and a white fuzzy body.They don't fly that I know of or have seen, but if you look closely and long enough, you can see movement. They are mostly located at the base of the tree in the crotch of a larger limb. This is a yearly occurrence.  I can not see any damage to the bark or leaves

Answer
Sounds like bark lice. A picture would help.

Bark Lice are more properly called Psocids (pronounced "SOSS-sids"). They are also called tree cattle because of their habit of living as a group on the bark of hardwoods, particularly oaks, and have been reported locally on citrus trees.  Large numbers of adults and nymphs are occasionally observed on tree trunks often living underneath the fine silken webbing they construct.  These insects do not attack the tree, but feed on lichens, fungi, and dead animal and plant matter.
Usually, the first noticeable sign of the presence of this insect is the fine silken webbing. The bark lice secrete this as a protective covering on the bark.  This silken webbing has a silvery sheen and may cover parts of the tree trunk and large limbs.  When the webbing is pulled off, it is not uncommon to see hundreds of these insects.  This webbing is not found on the twigs or leaves, and looks different than webbing produced by destructive caterpillars.
Webbing barklice are found throughout Florida, and along the Gulf coast from Texas and along the Atlantic coast north to South Carolina.  They are distant relatives of the booklice, which are household pests that can consume wood and paper products.  These outside Bark lice are not a threat to either the inside environment or to Florida Yards.   Populations of these tree cattle rise and fall with the seasons - cooler weather kills off many in the winter, and as springtime temperatures rise, food sources increase, and more webbing appears.  The greatest populations are found in the fall before the onset of cooler weather.
No control measures are recommended for these insects.  If the property owner objects to the webbing of these insects, a strong blast of water from a hose will dislodge them from the tree.  But as scavengers, they perform a valuable function in consuming excess accumulations of lichens, dead bark, and other materials found on the outside of the tree.  On trees that are regularly sprayed with insecticides for other pests, psocids will rarely be seen.  If the homeowner does insist on removing these insects, a Pest Control Operator may be contracted to apply a legal insecticide.
Here is a web site that gives more information and pictures of bark lice.
http://www.ag.auburn.edu/enpl/bulletins/barklice/barklice.htm