Year of the Fire Ant

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2023 will be the year of the fire ant for Caldwell County. Over the past few years, fire ants have been popping up in various places in the County. If you have not had problems with fire ants, I expect this year you will. Soon they will be another pest we all have to manage (or tolerate) just like the other invasive insects we have been blessed with (asian ladybugs, kudzu bugs, brown marmorated stink bugs, varroa mites, tracheal mites, longhorn Asian ticks, tiger mosquitoes, hemlock wooly adelgid, horn flies, face flies, etc).

The red imported fire ant (Solenopsis invicta) is native to Brazil. It was introduced into the United States at Mobile, Alabama about 1940. Fire ants first arrived in North Carolina in 1957. They started in Wilmington and have since spread westward (as well as up from South Carolina).

Currently, 74 of the 100 counties in North Carolina are considered home to these invasive stinging insects. To reduce the spread of these pests, the US Department of Agriculture created a quarantine zone. Fire ants can be transported with the movement of container plants, soil, hay, straw, mulch, earth moving equipment, and dirt. These materials are supposed to be inspected or treated before they move outside the USDA zone. There is limited funding to enforce these regulations. Catawba and Burke Counties are both in the quarantine zone, but Caldwell is currently not.

USDA Red Imported Fire Ant Zone. (Credit: USDA)

USDA Red Imported Fire Ant Zone. (Credit: USDA)

The red imported fire ant (RIFA) is small. Workers vary from 1/8 to 1/ 4 inch long. They are usually dark reddish brown in color. With a magnifying glass, it is easy to see the two nodes on the petiole. The petiole is the little segment between the thorax and abdomen. No other ant found in Caldwell County has this unique feature. However, you have to get real close to see these small bumps.

Red Imported Fire Ants can be identified by the two nodes on their petiole. (Credit: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS PPQ, Bugwood.org)

Red Imported Fire Ants can be identified by the two nodes on their petiole. (Credit: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS PPQ, Bugwood.org)

Fire ants nest in the ground. They make mounds. These mounds are the first sign of a fire ant infestation. They create their mounds in a way to capture solar energy to regulate the temperature for their developing brood (young fire ants). It is easy to recognize the brood when you kick the top off a mound. The brood look like small grains of rice. These “grains of rice” are the next generation. The ants will make the mounds taller after a rain to get the brood up out of the cool moist soil and better capture the energy of the sun. Fire ants don’t live in the woods. They only exist in open spaces.

Fire ant mounds will be more common in Caldwell County in 2023. (Credit: Seth Nagy)

Fire ant mounds will be more common in Caldwell County in 2023. (Credit: Seth Nagy)

Mechanical methods of fire ant control are ineffective. Digging up or tilling mounds has very little effect on the colony. Some on the internet suggest boiling water. Approximately 3 gallons of boiling hot water poured on a mound will eliminate nests about 60% of the time. However, 3 gallons of boiling hot water is more painful than a fire ant sting!

There are some interesting biological control options. My favorite is the Phorid fly. These are a natural parasite of fire ants in their home in Brazil. These flies lay their eggs near the ants’ heads. As the fly larvae develop, they kill the ant host. The ant’s head will fall off and serve as the capsule for the young fly larva to develop into a new adult.

When treating large areas, baits are the most effective and practical. A bait is food mixed with poison. This takes advantage of the fire ants’ foraging habit. They find the bait (poison laced food) and take it back to their nest. It is basically a variation on the trojan horse story. For home and commercial landscapes, Extinguish Plus is a bait that works very well. Be sure to read and follow the label.

As always, if you have questions about fire ant control or any other agricultural questions, please contact the Caldwell Extension Center (828-757-1290) or visit us online at caldwell.ces.ncsu.edu.

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— Seth Nagy is the Caldwell County Cooperative Extension director.

The Caldwell County Cooperative Extension Center, 120 Hospital Ave.,

#1 in Lenoir, provides access to resources of N.C. State University

and N.C. A&T State University through educational programs and

publications.