Not sure what you mean by ”light Spots”. If you have carpenter bees you will see 1/4 inch holes on the under side of the log or in the soffitts and fascia. They also make a mess were they come out of the hole and regurgitate their bellies of the wood fiber. This is why borate will not stop them since they do not digest the wood fiber. Best thing is to dust the hole with an insecticide and plug. More than likely they will drill another hole close by, but you can slow them down by attacking every hole that appears. Call Dave at 800-564-2987. He used to have a ”Bee Kit” with the insecticide and plugs for the holes.