Mound, Thatch, or Field - Same Ant

Friday July 27, 2012


Mr Pest Control


I have a problem with black mound ants at a school in Central NY. Could you please let me know the best choice of product and application methods? I have heard that you are to dig up the mound and place granules and mix it up few times and apply more granules. This is the first time I have dealt with mound ants.

Mr Pest Control


Mound ants are also referring to as Thatch, Thatching, or just Field ants, and most of them are in the genus Formica. They are large ants superficially similar to carpenter ants but with a distinct dip in the top of the thorax, whereas carpenter ants  have a thorax that is evenly rounded over the top. Thatch ants cannot sting, but they can bite, and once they create a little bite wound may spritz some formic acid onto that point to cause a stinging sensation. They almost always confine their activities to the outdoors and natural foods, in particular honeydew. These ants are well aware of where that honeydew comes from and they fiercely protect aphids from other insects that might eat or parasitize the aphids. Doing so they also keep away other pesky insects that feed on honeydew, such as yellow jackets and other wasps and ants. 

They turn the soil to create their colony, and in so doing create the large above-ground mounds that we notice. These may continue to be there and to enlarge for years, and if someone were to inadvertently stand on the mound he would immediately be attacked by the biting ants. A mound nest on a school property could become a liability for the school, so eliminating this nest is appropriate. Otherwise, since they so rarely enter structures the ants can normally just be left alone as beneficial parts of the local environment. 

Treating the mound itself is the correct treatment, generally using either a dust or a spray of contact insecticide and disturbing the surface pretty thoroughly so that you treat the whole mound and into it somewhat. A shovel or rake can be used to turn the surface over as the treatment is being done, taking care not to allow the ants to get up beneath your pants and onto your legs. You might rig up plastic bags as "leggings" around the bottom of your pants and even around the handle of whatever you use to mess with the mound to prevent the ants from climbing onto your hands. 

Keep in mind the state regulations on pesticide use on school properties, and be sure to stay within them. This likely means advance notice of this "emergency" treatment to many parents and posting the site prior to and following the treatment. Since you are not using the pesticide, in this situation, within any kind of enclosed station you would need to follow the regulations in place. 

Mr. Pest Control

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Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.