Jul 25, 2013 - 07:40 AM
Carpenter ants that are living in a tree usually have a nearby food source such as aphids or some other plant pest that they are feeding on. Using any bait and expecting them to go for it when they already have a natural food source is wishful thinking. Spraying the tree may be the best overall treatment plan, and you have to be careful what you use.
DO NOT USE ANY REPELLENT PESTICIDES such as Bifen, Talstar, etc. Use only non-repellent chemicals such as Imidichloprid. Products or brands that contain this chemical are Dominion, Premise, Merit and IMaxx Pro. You may need a backpack sprayer or some way of spraying up into the tree. If nothing else, spray as high as you can and completely saturate the trunk.
Then consider using the KM Ant Pro System around the base of tree and not on it. There is a lot of information on this system here, and it will help to control existing ants and also control future invading ants.