Carpenter ants are among the largest ants encountered in North America. They have a reputation primarily associated with wood damage, leading many to believe wood is their main food source. However, the answer to whether they are “sweet eating ants” is a definitive yes, as they are highly attracted to sugars and carbohydrates. This attraction often brings them into human structures while they search for easily accessible food. The widespread confusion about their habits stems from their unique nesting behavior, which is distinct from their actual diet.
The Truth About Carpenter Ant Diet
Carpenter ants are omnivores with a highly varied diet that shifts throughout the year to meet the needs of the growing colony. The adult worker ants primarily rely on carbohydrates, which serve as the fuel for their constant foraging and tunneling activities. Their most significant natural source of sugar is a sticky liquid called honeydew, a byproduct secreted by sap-sucking insects like aphids and scale insects.
While workers need sugar for energy, the colony also requires a steady supply of protein to sustain growth and reproduction. This protein is necessary for the queen to produce eggs and for the larvae to develop into new worker ants. They obtain this by scavenging dead insects or preying on small living invertebrates, such as spiders, caterpillars, and beetles.
The nutritional demands within the colony fluctuate seasonally. During the spring and early summer, when the queen is laying many eggs and the colony is ramping up production, the ants exhibit a stronger preference for protein-rich foods. Conversely, in late summer and fall, as larval development slows, their focus shifts back toward gathering carbohydrates to sustain the adult workers through the cooler months.
Why Carpenter Ants Invade Wood
The common association of these ants with wood is not because they consume it, but because they use it as a sheltered location for their nests. Unlike termites, carpenter ants cannot digest wood and gain no nutritional value from it. They use their powerful mandibles solely to excavate tunnels and chambers, known as galleries, to house their colony, queen, and developing young.
The ants prefer wood that is already softened by moisture damage or fungal decay because it requires less energy to chew through. This preference explains why infestations often begin in areas with water leaks, such as around window frames, leaky pipes, or poorly sealed decks. The resulting damage is characterized by smooth, polished tunnel walls, a distinct difference from the rough, mud-lined tunnels created by termites.
As the ants excavate their nests, they push the resulting debris out of small openings called “kick-out holes.” This material, often seen in small piles outside the nest entrance, is called frass, and it is a clear sign of their presence. Frass consists of fine wood shavings mixed with dead insect parts and other refuse from the colony. Observing frass confirms that the ants are actively tunneling, which can compromise the integrity of structural wood over time.
Utilizing Diet Knowledge for Effective Control
Understanding the omnivorous and shifting dietary needs of carpenter ants is fundamental to achieving successful pest control. Simply spraying foraging workers only eliminates a small fraction of the colony and does nothing to stop the queen or larvae. Effective elimination requires a strategy that exploits their foraging behavior to deliver a toxic agent directly to the nest.
This is accomplished through the use of slow-acting insecticidal baits, which workers willingly carry back to the colony via a process called trophallaxis, or food sharing. Because the ants require both protein and sugar, the most effective baits are often dual-action formulations that appeal to their varied appetites. Baiting success depends on offering the correct attractant based on the colony’s current need, such as a sugar-based liquid bait in the spring and a protein-based gel in the summer.
The toxic compound in the bait must be slow-acting, ensuring that the foraging worker does not die before returning to the nest and sharing the material with the queen and developing brood. When the queen and larvae consume the contaminated food, the reproductive cycle of the colony is disrupted. This method targets the entire colony at its source, which is the only way to achieve complete eradication, rather than just temporary surface control.