Black Ants in Evergreens

Black ants on evergreens may protect other, damaging insects.

Black ants on evergreens may protect other, damaging insects.

While most ants running up and down your prized evergreen aren't eating it, they may be protecting insects that are. Several species of insects feed on the sap inside the foliage and tender new shoots of needled and broadleaf evergreens and other plants, then excrete a sticky, sweet substance known as honeydew. Ants like the taste of honeydew so much they will defend the insects that produce it, driving away beneficial and predatory insects that could close down the banquet.

Black Ant Identification

Ants are divided into one-node and two-node species. Nodes are located between the fat hind end (abdomen), and the thorax, or main body to which the legs are attached. To identify the little black ant (Monomorium minimum), a two-node species, you'd also have to count the antenna segments. It has 12. Little black ants are 1/32 to 1/16 inches long. Leafcutter ants (Atta and Acromyrmex) in evergreens are shopping, not dining. These reddish to black ants cut leaf parts from the evergreen to take back to their colony, where it's used to farm a unique type of fungus. Leafcutters are normally found only in the southern portion of the United States. Carpenter ants (Camponotus pennsylvanicus) won't eat the evergreen, but simply tunnel into dead or water-soaked areas to build nests. These one-node ants are 1/4 to 1/2 inch long and fond of eating honeydew. Luckily for the squeamish, getting close enough to count ant parts isn't crucial to ant management.

Honeydew-Producing Insects

Common sap-feeding insects that exude honeydew include aphids (Homoptera Aphididae), pear-shaped insects about 1/16 inch long that feed in large colonies on the undersides of the leaves. Soft scales (Coccidae family) are less than 1/4 inch long, often round and convex. They may simply look like tiny, harmless bumps on the plant. Mealybugs are members of Homoptera, like aphids. Up to 3 millimeters long, many mealybug species feed on evergreens. The insects have waxy, meal-like coatings on their bodies or tails. Leafhoppers (Cicadellidae family) are 2 - 30 millimeters long and have rows of hairy spikes on their hind legs.

Removing Ant Attractants

Eliminating the insects that produce honeydew protects the evergreen from the damage they cause and renders the plant unattractive to ants. Spraying the evergreen foliage with a forceful stream of water from the garden hose every three days washes aphids, soft scale and other sap-sucking insects off the tree. In more severe cases, consider spraying the evergreen with soap sprays that smother and kill all insects present. Mix 2 tablespoons of baby shampoo in 1 gallon of water. To help the spray cling to the insects and foliage, add 2 tablespoons of cooking oil such as canola to the mixture. Do not spray in bright sunlight. Spray foliage thoroughly and repeat weekly as needed.

Keeping Ants Off the Evergreen

Barriers keep ants from accessing the evergreen. Products such as sticky tape or Tanglefoot, a sticky paste, should be applied completely around the trunk near the base to keep ants from climbing the evergreen. Be sure branch tips don't touch fences or other structures so the ants have no alternate access.

Killing Ants

Harsh chemical sprays can damage the evergreen and won't necessarily eliminate ants. The most effective way to eliminate ants, according to the California Statewide Integrated Pest Management website, is to use poisoned ant bait stations. Bait stations are prefilled with attractant and poison, and may be sited near the evergreen, on ant trails or near colonies. Worker ants bring other ants to the bait station, and these ants poisoned bait back to the colony. It takes time to eliminate the colony, so be patient. Bait stations may be single-use or refillable. For heavy infestations or large colonies, refillable bait stations may be more effective.

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