Yes you can add it but it is more about supplementing the plants carbohydrates as they get all used up during flowering. i have heard a lot of people using molasses but there are a lot of better sources of carbs for your plant.
I use Carbo load made by advanced nutrients. This exactly matches the plants carbohydrates and eliminates any waste from using things such as molasses. I start using this product about a week or two into flowering, and continue until the final flush.
This serves two pursoses for me as I also utilize benefical bactaria and fungi in my grow to help fight disease and stimulate explosive root growth. This carbo load also feeds them so that they thrive because plant carbohydrate is what they eat.
The carbohydrates are dissolved into the nutrient solution, and I have never heard of anyone getting mice or bugs from using carbohydrate supplements. The key to keepings bugs and mice away is cleanliness.
People add all sorts of sweet things to their plants during budding. It can help to increase potency a bit.
A neighbor pours Coke on his plants.
I have a friend who owns a hydro store and is the most expert grower I know. He recommends adding a few ounces of unsweetened pineapple juice per gal of water/nutrients during the last month of flowering.
I mainly use carbs because they give the plant extra energy to produce bigger buds and more resin. I also as stated use carbs to feed the little community of microorganisms that I add to my grow. (piranah + Voodoo juice)