Cedar mulch benefits plants by reducing weed growth, retaining soil moisture and maintaining soil temperature. Wood mulches, however, also attract their share of insects, including carpenter ants.
About Carpenter Ants
Carpenter ants help the wood decomposition process by building nests in decayed stumps, hollow trees and dead limbs. Despite common belief, carpenter ants don't live beneath or in layers of wood-chip mulch. If you spot them roaming in mulched areas, they're probably just searching for moisture or foraging for dead bugs.
Treatment for Them
If you want to get rid of carpenter ants, treat them near their nesting site and not in cedar mulch. Carpenter ants like sweets. So setting a sugar-based bait station near their nest can trap the insects, but carefully read and follow instructions and safety precautions on the bait station's label. A bait station should not be used in an area where children and pets will be. Check the bait station regularly, and replace it as needed.
Although carpenter ants build their main nests outdoors, they may form satellite colonies in a house if they find a way inside it. Keeping mulch at least 3 inches from your home's foundation can keep the pests from finding an entrance into your indoor living space.