Fire ant invasion? (Kathy, Devils Lake, North Dakota, USA)


I live in the Northern USA and wanted to know if Fire Ants will ever be a pest in my yard?


The Red Imported Fire ant, Solenopsis invicta, is an introduced pest in the United States from South America. There are also native fire ants (species of the genus Solenopsis) found in many parts of the world, including the United States. Although the Red Imported Fire ant is an introduced pest in many parts of the United States, Australia, and some islands, it is unlikely you will ever have the invasive Red Imported Fire ant in the northern US since they are not able to survive long winters with hard freezes. Red Imported Fire ants are considered "hot climate specialists". This means they are unlikely to survive in your North Dakota yard, but may still be able to survive in places with temperature controlled environments like greenhouses. This species has even made the list of "100 of the World's Worst invaders": http://www.issg.org/database/species/search.asp?st=100ss

Soleopsis_invicta_AlexWild.jpg
Solenopsis invicta - Red Imported Fire ant. Photo by Alex Wild (www.alexanderwild.com).


Where in the US are Red Imported Fire ants found?

The Red Imported Fire ant is thought to have been first introduced in the US in the late 1930's in the port of Mobile, Alabama. They are considered a serious problem due to many factors that include their ability to spread rather rapidly, their painful sting, aggressive behavior, and damage to some agricultural crops and livestock. In the United States fire ants have spread from Alabama across the southern US and into isolated areas of California, which has resulted in quarantines of movement of some products like soil and plants to help stop the spread of these invasive ants. Although we are not certain how much further north and west they will spread, we do know that they will not be able to survive outside in areas with long, cold winters.


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Distribution of Red Imported Fire ants in USA. Map from: http://www.invasivespeciesinfo.gov/animals/rifa.shtml


Why are they called Fire ants?

Well if you have ever been stung by a Fire ant you can answer this question. Fire ants get their common name from the fact that when they sting you it feels as though you have been touched by a red-hot flame. These ants bite onto you (or other enemies, intruders or prey) with their jaws and then inject a dose of venom with the sting on the rear end of their body. Their sting is not only painful, but for some people this can be a real problem since it can result in anaphylactic shock or even death in very extreme cases. Also most people develop an itchy, puss filled bump after being stung.

Fire ant stings USDA.jpg

Fire ant stings. Photo from: http://www.ars.usda.gov/fireant/project.htm

How can I identify a Fire ant?

Telling fire ants apart from other ants can be difficult since they look like most ordinary red/brown ants, although AntWeb and a microscope will help. Two of the key signs are their behavior (they are very aggressive and sting readily) and mound-shaped nests. Each of these mounds can contain up to 300,000 individual ants.

Fire ant mound AlexWild.jpg

Fire ant mound. Photo by Alex Wild (www.alexanderwild.com).

Although this species is considered an invasive pest in some areas like the United States and Australia, it is important to keep in mind that they are not all bad. In their native range of South America it is one of many important ants in the ecosystem. For more information on the Red Imported Fire Ant, check out this webpage which contains many informative links:
http://www.invasivespeciesinfo.gov/animals/rifa.shtml

- Corrie Moreau & the AntAsk Team

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