Even though you may see them in large numbers during the day, Carpenter Ants are nocturnal and most active from about 10 PM to 3AM. This is when they are most likely to be foraging for food from dead insects, and sometimes even from live ones.
The worker Carpenter Ant will ingest its food in a liquid form, then return to the nest, and feed the queen and the larvae by regurgitating the food. Since they ingest the food, liquid baits do not work well on this species of ant. Poison baits work rather quickly resulting in killing one ant at a time. This is not a very effective means of control. By comparison, sugar ants do not ingest their food but rather carry it back to feed the larvae and queen destroying the colony. With Sugar Ants, liquid baits are a very effective tool but is almost useless in the control of Carpenter Ants.
Carpenter Ants do not eat wood because they are not able to digest cellulose. They make tunnels through the wood using their mandibles and the excessive wood is removed and discarded. This is why you may find piles of sawdust near active areas of ant infestations. When they begin to tunnel through wood they usually prefer damp or slightly rotted wood to make their nest in. As the colony grows, the worker ants will start tunneling from the damaged wood and will continue making galleries and tunnels even in sound and undamaged wood.