Diagnosing Ant Problems

Ant Problems Are Hard To Define

An “ant problem” is hard to define, because a healthy home landscape has lots of ants busy doing all kinds of good. They are efficient scavengers of pest insect eggs, small animal carcasses and other natural decaying debris in and on the soil. Most of the time they go about their business out of the site and awareness of homeowners. Worker ants forage for food over a wide area. Some ant species feed on young succulent vegetables, while others eat almost anything, including seeds, buds and flowers. The most obvious sign of ants is their nest mounds. These mounds occur in lawns and gardens, and extensive underground excavations can eventually undermine pavement.

Commonly, problems involving ordinary backyard ants are usually related to their being suddenly obvious, or in the wrong place. When nests become overcrowded and overflow, residents gather to move to a new area. These swarms are a nuisance and an eyesore. Also, when certain types of ants discover honeydew that aphids produce while feeding on plants, they rally to the site to enjoy the sweet treat. While they do not harm the plants, they mar its appearance and the aphid pests they protect proceed with their destruction.

Symptoms That There May Be An Ant Problem

Mounds of loose soil in the lawn: Lawns may be harmed by a colony of ants loosening the soil as they construct small mounds over their nesting areas. The roots of adjacent grass plants may dry out and die. Plants in a flower garden or vegetable garden can suffer the same way, as ant tunnels expose too many roots to air.

Plant leaves and stems infested with pest insects: Some kinds of ants are attracted to the sweet honeydew excreted by some aphids, scale, and mealybug pests as they feed on plant tissues. These ants have learned how to actually herd the insects on a plant, so they can protect them from their natural beneficial predators such as ladybugs and lacewings. Consequently, plants suffer from sustained pest insect infestation.
Erosion of soil in stone walls: Because ants prefer to nest at the edge of their territory, they frequently nest in and around stones or pavement, especially preferring stone walls. As they hollow out a network of tunnels and chambers in the soil behind the stone walls, they sometimes inadvertently undermine its support. Stones begin to dislodge and low walls may collapse in places. Piles of granular soil accumulate at the base of the stone walls.

Plant Damage Caused By Ants

Ants inadvertently promote plant damage as they go about the business of surviving. They sometimes transmit plant diseases such as botrytis blight and fire blights as they roam over plants. Also, by protecting such plant pests as aphids, mealybugs, and scale, they indirectly promote plant damage on a wide range of ornamental plants.

Citrus and fig trees (blossoms and buds damaged)
Corn (roots attacked)
Turfgrasses (nests, root damage)
Pines, other trees (leaves damaged)
Small trees and shrubs (killed outright by girdling or leaves stripped by leafcutting ants)
Vegetables (seeds and seedlings attacked)

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