At the Cooperative Extension office, we have been receiving a large number of requests for information on dealing with ants. Thousands of these little insects seem to appear out of nowhere, indoors and out. Ants live in massive colonies, with a queen who is the mother of all. There are many types; some entomologists believe there may be 22,000 different species, comprising ten quadrillion (equal to a thousand trillion) individual ants spread across the planet.
There is some good news about ants. They do turn over the soil, helping to aerate it and improve drainage, a very big concern for many Southern Nevada gardeners. Most people would probably be happier opting for a rototiller or a garden fork rather than relying on insects, but that is not an option. The other good thing, or at least not a bad thing, is that they are generally not a problem for plants. Some will eat sweet fruits and vegetables, but many prefer meat (other insects). There are some that are leaf cutters, but these are not widespread in this area. Some will bite mammals such as us and our pets – fire ants and army ants come to mind.
Possibly the worst problem ants pose for gardeners is that they will “farm” aphids. Aphids are sucking pests that will harm plants; even worse, they are a very effective delivery system for plant viruses. They also secrete a kind of honeydew the ants feed to their young. Ants will groom the aphids, care for them during the winter and reintroduce them to the garden in spring.
Whether ants are vegetarian or carnivore, few gardeners enjoy seeing a regiment of them in a raised bed or under a tree. Controlling them becomes a major issue. Different methods are efficacious for some varieties but a few things are effective on most.
The best method will also depend on where the ant hill has formed. It is easier in some ways to control those appearing indoors. First get rid of their trails by washing the path they follow. Ants leave a trail from their home that they and their sisters follow. These chemical trails are disturbed by soap and water. Caulk or block the cracks or openings where they have entered.
On sidewalks or other unplanted areas, boiling water or steam will murder most of the population. Some references state that they can be controlled by regularly flooding the colony, but that requires more water than we should be using. Inside or out, it is important to wash away their trails.
Growing the herb tansy, and possibly some of its cousins, is one recommendation, as its dried leaves can repel them. The plant is also a safe haven for predatory insects such as ladybugs and lacewings.
Bait traps are effective. Many of these contain a low dose of boric acid, which is not only a nerve and stomach poison, but will also dry out the insects. If they are not immediately slain, ants carry the boric acid back to their homes where it will slowly kill the colony. Best of all, it is almost nontoxic to people.
Dr. Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.
