Ask the Expert

RYAN NEFF, Ph.D, West Coast Technical Field Specialist, MGK

Q What is the most common pest ant in the United States?

A This is a difficult one to answer: Do you go by total number of accounts that treat for a certain ant? The geographic range a particular species covers? Total abundance in the U.S.? If you go by geographic range, the most common pest ant is either the odorous house ant (OHA) or various species of carpenter ants. If you live in California, the Argentine ant is the most prevalent species. Doing pest control throughout the Southeast means dealing with the ever-present imported fire ant. But state-for-state, OHA and carpenter ants take the crown. OHAs and many species of carpenter ants are native to North America and are thus adapted to the different conditions across the continent. While winter often signals relief from ant-related pest issues, OHA and carpenter ants will often nest in wall voids, attics and other insulated indoor areas. While slow-killing sprays or baits are usually recommended for large exterior/interior infestations that occur in the summer, for these scenarios, dusts, aerosols and/or mechanically-generated aerosol machines often achieve the best results.

Q My customer has trees and shrubs that are in contact with the structure and they’re unwilling to cut them back. Is there anything I can do?

A Absolutely. In fact, this gives you a great opportunity to show you are the "Pied Piper" of ant management. Think about it: The ants are using the trees and shrubs as bridges to bypass your standard applications around the foundation of a structure. On the West Coast, this is often observed with Argentine, OHA, velvety tree, carpenter and rover ants. In the Southeast, this can be observed with imported fire ants, rover ants, crazy ants, ghost ants, white-footed ants and many other species (the Southeast has a much higher diversity and abundance of ants compared to the western U.S., with the exception of Arizona). Treat around the base of each tree with a slow-acting, aka "non-repellent" product. This forces the ants to cross your material as they travel to whatever is attracting them indoors. For more rapid and thorough control, consider using a bait. The bait can be applied near where your slow-acting product has been applied, or over it once it has dried. In addition to attracting ants over your slow-acting material you will also coax ants out of the house. Ants will go the path of least resistance and if you give them a good food source closer to home they won’t be able to turn it down.

Q I have a commercial account with large numbers of crape myrtles surrounding a structure. Every summer, I have ant call-backs at this location and I’m certain the aphids and scales are contributing to the high ant numbers outdoors. How can I get rid of them so the ants don’t have an outdoor food source?

A This applies not only to crape myrtles but any trees or shrubs that have significant numbers of aphids, scales, whiteflies and other hemipteran pests associated with them. The first thing you can do is a root drench early in the season with a neonicotinoid. It takes a little while, but the insecticide will move through the plant’s phloem and into the parts of the plant fed on by honeydew-producing insects. You may also do foliar applications, as many ant control products are labeled for and better suited to such an application. Keep in mind this should never be done on edible plants, herbs, fruits/vegetables or flowering plants. Not only will controlling honeydew-producing insects keep ant populations lower than they would otherwise be, it will also affect the amount of food paper wasps and yellowjackets can obtain. It will also eliminate a lot of that pesky "sap" on patron and employees' vehicles.