The best product for carpenter bees and wasps is Demon WP, due to its long residual effect which can be 2-3 months before the UV light of the Sun begins to breakdown the chemicals effectiveness.
Apply directly to walls, window screens, and other exterior resting areas as a residual surface treatment. Use caution when treating nests of stinging insects as Demon WP does not provide instant knockdown. For best results, treat bee, wasp and hornet nests late in the day when most insects will be present. Allow 2-3 days for colony to die.