Question
Hi, I have a maple tree (not sure what species), brighter green leaves.  Every year it gets these protuding things on the leaves.  They are about 1/8" long, pink to red in color. Some leaves have 5-10 others up to 50.  Treated with Sevin, didn't seem to help.

Answer
These are maple spindle galls. Maple spindle gall is caused by mites. The galls are found on soft maples and sugar maples. The galls are about 1/5 inch long and about as thick as pencil lead. The galls stand erect and are easily seen and identified.

Other than the mere aesthetic damage and possible early leaf drop, no significant damage is done to the health of maple trees. Following a mild winter, damage from these leaf galls can be excessive but affected trees often send out new leaves to replace the damaged ones. Since these leaf galls of maple do not cause any real harm to the trees, control measures are not generally needed.

Several insecticides and miticides are registered for control of gall mites (eriophyid mites) and gall midges. If these products are to be used, they have to be applied precisely when the new leaf buds are opening. Most sprays have little, if any, effect because the window of opportunity is very short. Once the gall has formed, it is too late to make an application. That is why the Sevin had little effect.  

I would not worry about the leaf galls.