Can Carpenter Ants Damage Vegetable Plants?

Habits

• Carpenter ants don't eat wood, but they chew it to construct tunnels, creating extensive galleries. Ants forage at night, preferring foods rich in proteins and sugars. They eat dead or live insects, fruit juices, nectar from flowers and honeydew excreted by pest insects such as scale insects, aphids and mealybugs. They are so fond of the honeydew that they take care of aphids in ant-tended aphid farms, and they herd and protect the aphids. This is the main negative effect they can have on vegetable gardens. Ants may also beat you to ripe, sugary fruits for the juices. Carpenter ants rarely forage more than several hundred feet from their nest.

Life Cycle

• A nest begins with a single mated queen ant. She finds a nest site like a rotten log, tree stump, damaged tissues of a living tree or a woodpile. She begins to lay eggs, and they hatch into worker ants, who then forage for food, tend the young and build the tunnels in wood. Workers defend the nest by biting with their powerful jaws and spraying formic acid on the bite, which can be painful. Ants undergo complete metamorphosis, going from egg to larva to pupa to adult. Only larvae eat solid food, changing it to liquid and passing it back to workers. A nest can grow to 2,000 adults in about six years, when it is large enough to produce winged male and female ants. Carpenter ants don't damage healthy woody plants in your garden, but may invade untreated landscaping timbers that develop areas of wet wood.

Kinds of Carpenter Ants

• Carpenter ants are more common in forested or mountainous areas, but can be found anywhere wood exists for nesting sites. Two large black carpenter ants are the large western black carpenter ant (Camponotus modoc), which has a black body and reddish legs, and the black carpenter ant (Camponotus pennsylvanicus). Another large carpenter ant (Camponotus vicinus) is colored brown and black. A smaller carpenter ant (Camponotus clarithorax) has yellow and black coloration. Carpenter ants seen indoors can be flying reproductives that enter during swarming or foragers from a satellite colony somewhere in the wood of the house.

Management and Considerations

• Replace any decaying or damaged wood on structures so the damaged wood doesn't attract carpenter ants. Caulk any crevices, holes or other possible entry points for ants. Reduce garden populations of honeydew-producing insects to cut down on carpenter ant populations, and don't leave out food attractive to carpenter ants, such as sugary substances, meat or fat. Keep stored firewood off the ground and get rid of earth-to-wood connections that would allow ants to access structures. Because carpenter ants eat insects, they may remove some harmful insects from your garden. Ants in turn provide food to beneficial garden creatures like horned lizards, other lizards, toads and birds such as flickers.