View source for Fire ant

{{short description|Genus of red ants}}
{{redirect|Red ant|the species ''Pogonomyrmex barbatus''|Red harvester ant|other uses|Fire ant (disambiguation)}}
{{pp-pc1|small=yes}}
{{Automatic taxobox
| fossil_range = {{fossil range|Early Oligocene|Recent}}
| image = Fire ants 01.jpg
| taxon = Solenopsis (ant)
| authority = [[John Obadiah Westwood|Westwood]], 1840
| type_species = ''Solenopsis geminata''
| type_species_authority = Fabricius, 1804
| diversity_link = #Species
| diversity = 201 species
| diversity_ref = <ref name="AntCat">{{AntCat|429752|''Solenopsis''|2014|accessdate=20 July 2014}}</ref>
}}

'''Fire ants''' are several species of [[ant]]s in the [[genus]] '''''Solenopsis''''', which includes over 200 species. ''Solenopsis'' are [[Stinger|stinging]] ants, and most of their [[common name]]s reflect this, for example, '''ginger ants''' and '''tropical fire ants'''. Many of the names shared by this genus are often used interchangeably to refer to other species of ant, such as the term '''red ant''', mostly because of their similar coloration despite not being in the genus ''Solenopsis''. Both ''[[Myrmica rubra]]'' and ''[[Pogonomyrmex barbatus]]'' are common examples of non-Solenopsis ants being termed red ants.<ref>{{cite web|last1=Reins|first1=Dusty|title=Species: Pogonomyrmex barbatus - Red Harvester Ant|url=https://www.wildcatbluff.org/content/species-pogonomyrmex-barbatus-red-harvester-ant|publisher=Wildcat Bluff Nature Center|access-date=30 December 2014|archive-url=https://web.archive.org/web/20150402130103/https://www.wildcatbluff.org/content/species-pogonomyrmex-barbatus-red-harvester-ant|archive-date=2 April 2015|url-status=dead}}</ref>

None of these common names apply to all species of ''Solenopsis'' nor exclusively to species of ''Solenopsis''; for example, several species of [[weaver ant]]s of the genus ''[[Oecophylla]]'' in [[Southeast Asia]] are colloquially called "fire ants" because of their similar coloration and painful bites, but the two genera are not closely related. ''[[Wasmannia auropunctata]]'' is another unrelated ant more commonly called the "little fire ant" due to its potent sting.<ref>{{cite web|title=''Wasmannia auropunctata''|url=https://www.hear.org/species/wasmannia_auropunctata/|publisher=Hawaiian Ecosystems at Risk project (HEAR)|access-date=9 July 2015}}</ref>

==Appearance==
[[Image:Redant.JPG|thumb|left|250px|Fire ant mound|alt=Fire ant mound]]
[[File:CSIRO ScienceImage 11133 Tropical fire ant.jpg|thumb|Detail of the head (''Solenopsis geminata'')|alt=Detail of fire ant head]]
The bodies of mature fire ants, like the bodies of all typical [[Insect morphology|mature insects]], are divided into three sections: the head, the [[thorax]], and the abdomen, with three pairs of legs and a pair of [[antenna (biology)|antennae]]. Fire ants of those species invasive in the United States can be distinguished from other ants locally present by their copper brown head and thorax with a darker abdomen. The worker ants are blackish to reddish and their size varies from {{convert|2|to|6|mm|in|abbr=on}}. In an established nest these different sizes of ants are all present at the same time.<ref name=qldgov>{{cite web|title=Fire ant identification|url=https://www.daff.qld.gov.au/plants/weeds-pest-animals-ants/invasive-ants/fire-ants/general-information-about-fire-ants/identification|publisher=Department of Agriculture, Fisheries and Forestry (Queensland Government)|access-date=30 December 2014|date=30 July 2013|archive-date=18 February 2014|archive-url=https://web.archive.org/web/20140218184045/https://www.daff.qld.gov.au/plants/weeds-pest-animals-ants/invasive-ants/fire-ants/general-information-about-fire-ants/identification|url-status=dead}}</ref>

''Solenopsis'' spp. ants can be identified by three body features—a [[Petiole (insect)|pedicel]] with two nodes, an unarmed [[propodeum]], and antennae with 10 segments plus a two-segmented club.<ref>{{cite web|title=Red Imported Fire Ant - UC Statewide IPM Program|url=https://www.ipm.ucdavis.edu/PMG/r785301611.html|publisher=University of California Agriculture & Natural Resources|access-date=30 December 2014|date=25 April 2014}}</ref> Many ants bite, and formicine ants can cause irritation by spraying [[formic acid]]; myrmecine ants like fire ants have a dedicated venom-injecting [[Stinger|sting]], which injects an alkaloid venom, as well as [[Mandible (insect mouthpart)|mandibles]] for biting.<ref>{{cite journal|last1=Yi|first1=GB|last2=McClendon|first2=D|last3=Desaiah|first3=D|last4=Goddard|first4=J|last5=Lister|first5=A|last6=Moffitt|first6=J|last7=Meer|first7=RK|last8=deShazo|first8=R|last9=Lee|first9=KS|last10=Rockhold|first10=RW|title=Fire ant venom alkaloid, isosolenopsin A, a potent and selective inhibitor of neuronal nitric oxide synthase|journal=International Journal of Toxicology|date=2002|volume=22|issue=2|pages=81–6|pmid=12745988|doi=10.1080/10915810305090|s2cid=23324548|doi-access=free}}</ref>

==Behavior==
[[File:Solenopsis.jpg|thumb|left|A fire ant worker, queen, and male (clockwise from bottom left)|alt=Fire ant worker, queen, and male]]
A typical fire [[ant colony]] produces large mounds in open areas, and feeds mostly on young plants, insects and seeds. Fire ants often attack small animals such as small lizards and can kill them. Unlike many other ants, which bite and then spray [[acid]] on the wound, fire ants bite only to get a grip and then sting (from the abdomen) and inject a toxic [[alkaloid]] [[venom]] called [[solenopsin]], a compound from the class of [[piperidines]]. For humans, this is a painful sting, a sensation similar to what one feels when burned by [[fire]] (hence the name), and the after-effects of the sting can be deadly to sensitive people.<ref name=consideration>{{cite web|last1=Drees|first1=Bastiaan M.|title=Medical Problems and Treatment Considerations for the Red Imported Fire Ant|url=https://fireant.tamu.edu/files/2011/12/FAPFS023_2002rev_Medical.pdf|publisher=[[Texas A&M University]] (Texas Imported Fire Ant Research and Management Project)|access-date=30 December 2014|date=December 2002}}</ref> Fire ants are more aggressive than most native species, so have pushed many species away from their local habitat. One such species that ''Solenopsis'' ants parasitically take advantage of are bees, such as ''[[Euglossa imperialis]]'', a nonsocial orchid bee species, from which the ants enter the cells from below the nest and rob the cell's contents.<ref>{{cite journal | last1 = Roberts | first1 = R. B. | last2 = Dodson | first2 = Calaway H. | year = 1967 | title = Nesting biology of two communal bees, Euglossa imperialis and Euglossa ignita (Hymenoptera: Apidae), including description of larvae | journal = Annals of the Entomological Society of America | volume = 60 | issue = 5| pages = 1007–1014 | doi=10.1093/aesa/60.5.1007}}</ref>

These ants are renowned for their ability to survive extreme conditions. They do not hibernate, but can survive cold conditions, although this is costly to fire ant populations as observed during several winters in Tennessee, where 80 to 90% of colonies died due to several consecutive days of extremely low temperatures.<ref>{{cite book|author= Walter R. Tschinkel |title= The Fire Ants |url=https://archive.org/details/fireants0000tsch |url-access= registration|publisher=[[Belknap Press]] of Harvard University Press|location= Cambridge|year= 2006|isbn= 978-0-674-02207-2|page=[https://archive.org/details/fireants0000tsch/page/89 89]|author-link= Walter R. Tschinkel}}</ref>

Fire ants have been known to form [[Mutualism (biology)|mutualistic]] relationships with several species of [[Lycaenidae]] and [[Riodinidae]] butterflies.<ref name=":1">{{Cite journal|last1=Horvitz|first1=Carol C.|last2=Turnbull|first2=Christine|last3=Harvey|first3=Donald J.|date=1987-07-01|title=Biology of Immature Eurybia elvina (Lepidoptera: Riodinidae), a Myrmecophilous Metalmark Butterfly|journal=Annals of the Entomological Society of America|volume=80|issue=4|pages=513–519|doi=10.1093/aesa/80.4.513|issn=0013-8746}}</ref><ref name=":0">{{Cite web|url=https://animaldiversity.org/accounts/Lycaena_rubidus/|title=Lycaena rubidus|last=Watt|first=Loren|date=2001|website=Animal Diversity Web}}</ref> In ''[[Lycaena rubidus]]'', the larvae secrete a fluid that is high in sugar content. Fire ants bring the larvae back to the nest, and protect them through the pupal stage in exchange for feeding on the fluid.<ref name=":0" /> In ''[[Eurybia elvina]]'', fire ants were observed to frequently construct soil shelters over later instars of larvae on inflorescences on which the larvae are found.<ref name=":1" />

Fire ants nest in the [[soil]], often near moist areas, such as [[Bank (geography)|river bank]]s, [[pond]] shores, watered [[lawn]]s, and [[highway]] shoulders. Usually, the nest will not be visible, as it will be built under objects such as [[timber]], logs, rocks, or bricks. If no cover for nesting is available, [[dome]]-shaped mounds are constructed, but these are usually only found in open spaces, such as fields, parks, and lawns. These mounds can reach heights of {{cvt|40|cm}},<ref name=qldgov/> but can be even higher on heavier soils, standing at {{cvt|1.0|m}} in height and {{cvt|1.5|m}} in diameter.<ref name=Minnesota/> Colonies are founded by small groups of queens or single queens. Even if only one queen survives, within a month or so, the colony can expand to thousands of individuals. Some colonies may be [[Polygyny in nature|polygynous]] (having multiple queens per nest).<ref>{{cite journal|last1=Kintz-Early|first1=Janet|last2=Parris|first2=Leslie |last3=Zettler|first3=Jennifer|last4=Bast|first4=Josh|title=Evidence of polygynous red imported fire ants (Hymenoptera: Formicidae) in South Carolina|journal=Florida Entomologist|date=September 2003|volume=86|issue=3 |pages=381–382|doi=10.1653/0015-4040(2003)086[0381:EOPRIF]2.0.CO;2 |url=https://journals.fcla.edu/flaent/article/view/75220/72878 |access-date=30 December 2014|doi-access=free}}</ref>

Fire ants are resilient and can survive floods. During [[Hurricane Harvey]] in [[Texas]] in 2017, clumps of fire ants, known as rafts, were seen clumped together on the surface of the water. Each clump had as many as 100,000 individual ants, which formed a temporary structure until finding a new permanent home.<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |title= Floating fire ants form rafts in Houston floodwaters|url=https://www.bbc.com/news/world-us-canada-41093596 |work=BBC |location=London |date= August 2017|access-date= 30 August 2017 }}</ref>  Ants clumped in this way will recognize different fluid flow conditions and adapt their behavior accordingly to preserve the raft's stability.<ref>{{cite news |last1=Ouellette |first1=Jennifer |title=Fire ant rafts form because of the Cheerios effect, study concludes |url=https://arstechnica.com/science/2022/09/fire-ant-rafts-form-because-of-the-cheerios-effect-study-concludes/ |access-date=18 October 2022 |work=Ars Technica |date=16 September 2022 |language=en-us}}</ref> 

Fire ants dig tunnels efficiently using about 30% of the population of the colony, thereby avoiding congestion in tunnels.<ref>{{Cite news|url=https://www.nytimes.com/2018/08/16/science/ants-worker-idleness.html|title=The Secret to Ant Efficiency Is Idleness|last=Gorman|first=James|date=2018-08-16|work=The New York Times|access-date=2019-01-17|issn=0362-4331}}</ref>

==Queens, males and workers==
[[Image:Fire ant queens 3589.jpg|thumb|250px|''Solenopsis'' winged reproductive females, queens and workers|alt=Solenopsis winged reproductive females, queens and workers]]

===Queen===
Fire ant queens, the reproductive females in their colony, also are generally the largest. Their primary function is reproduction. Typically, a fire ant queen will seek to establish a new colony following a nuptial flight, wherein it will use its special venom to paralyze offending competitors,<ref name=":2">{{Cite journal|last1=Fox|first1=Eduardo G.P.|last2=Wu|first2=Xiaoqing|last3=Wang|first3=Lei|last4=Chen|first4=Li |last5=Lu|first5=Yong-Yue|last6=Xu|first6=Yijuan|date=February 2019|title=Queen venom isosolenopsin A delivers rapid incapacitation of fire ant competitors|journal=Toxicon|volume=158|pages=77–83 |doi=10.1016/j.toxicon.2018.11.428|pmid=30529381|bibcode=2019Txcn..158...77F |s2cid=54481057}}</ref> in the absence of workers for defense. Fire ant queens may live up to seven years and can produce up to 1,600 eggs per day, and colonies will have as many as 250,000 workers.<ref name=Minnesota/><ref>{{cite book|last1=Vinson|first1=S.B.|last2=Sorenson|first2=A.A.|title=Imported Fire Ants: Life History and Impact |date=1986|publisher=The Texas Department of Agriculture|location=Austin, Texas}}</ref> The estimated potential life span is around 5 years and 10 months to 6 years and 9 months.<ref>{{cite journal|last1=Tschinkel|first1=Walter R.|title=Fire Ant Queen Longevity and Age: Estimation by Sperm Depletion|journal=Annals of the Entomological Society of America|date=1987|volume=80|issue=2|pages=263–266|url=https://bio.fsu.edu/~tschink/publications/1987-2.pdf|access-date=30 December 2014|doi=10.1093/aesa/80.2.263}}</ref> Young, virgin fire ant queens have wings (as do male fire ants), but they often cut them off after mating. Occasionally, a queen will keep its wings after mating and through her first year.

===Males (drones)===
Male fire ants mate with queens during a nuptial flight. After a male has successfully inseminated a queen, he will not get accepted back to the mother colony, and will eventually die outside the nest.<ref>{{Cite web |url=https://fireant.tamu.edu/ |title=Texas Imported Fire Ant Research and Management Project  |website=fireant.tamu.edu |access-date=2019-04-13}}</ref>

===Workers===
The other roles in an ant colony are usually undertaken by workers. Fire ant workers are haphazardly divided into different size classes, namely minima, minor, media, and major workers.<ref>{{Cite journal|last1=Fox|first1=Eduardo Gonçalves Paterson|last2=Pianaro|first2=Adriana|last3=Solis|first3=Daniel Russ|last4=Delabie|first4=Jacques Hubert Charles|last5=Vairo|first5=Bruno Cunha|last6=Machado|first6=Ednildo de Alcântara|last7=Bueno|first7=Odair Correa|date=2012|title=Intraspecific and Intracolonial Variation in the Profile of Venom Alkaloids and Cuticular Hydrocarbons of the Fire Ant Solenopsis saevissima Smith (Hymenoptera: Formicidae)|journal=Psyche: A Journal of Entomology|volume=2012|pages=1–10|doi=10.1155/2012/398061|issn=0033-2615|doi-access=free|hdl=11449/73386|hdl-access=free}}</ref> The major ants are known for their larger size and more powerful mandibles typically used in macerating and storing food items (i.e. as repletes), while smaller workers take care of regular tasks (the main tasks in a colony are caring for the eggs/larvae/pupae, cleaning the nest, and foraging for food).<ref name=Minnesota>{{cite web|last1=Lockley|first1=Timothy C.|title=Imported Fire Ants|url=https://ipmworld.umn.edu/chapters/lockley.htm|publisher=University of Minnesota (IPM World Textbook)|access-date=30 December 2014|url-status=dead|archive-url=https://web.archive.org/web/20141230080227/https://ipmworld.umn.edu/chapters/lockley.htm|archive-date=30 December 2014}}</ref> However, ''[[Solenopsis daguerrei]]'' colonies contain no workers, as they are considered social parasites.<ref>{{cite journal|last1=Briano|first1=Juan A.|last2=Calcaterra|first2=Luis A.|last3=Wojcik|first3=D.P.|last4=Williams|first4=D.F.|last5=Banks|first5=W.A.|last6=Patterson|first6=R.S.|title=Abundance of the Parasitic Ant ''Solenopsis daguerrei'' (Hymenoptera: Formicidae) in South America, a Potential Candidate for the Biological Control of the Red Imported Fire Ant in the United States|journal=Environmental Entomology|date=1997|volume=26|issue=5|pages=1143–1148|url=https://www.researchgate.net/publication/233508278|access-date=30 December 2014|doi=10.1093/ee/26.5.1143}}</ref>

==Invasive species==
{{details|topic=invasive species|Red imported fire ant}}
[[File:Fire Ant Festival sign, Ashburn, GA, US.jpg|thumb|Sign for the Fire Ant Festival in [[Ashburn, Georgia]] |alt=Fire Ant Festival Sign]]

Although most fire ant species do not bother people and are not invasive, ''Solenopsis invicta'', known in the United States as the [[red imported fire ant]] (or RIFA), is an invasive pest in many areas of the world, including the [[United States]], [[Australia]], [[China]] and [[Taiwan]].<ref>{{cite journal|last1=Ascunce|first1=M. S.|last2=Yang|first2=C.-C.|last3=Oakey|first3=J.|last4=Calcaterra|first4=L.|last5=Wu|first5=W.-J.|last6=Shih|first6=C.-J.|last7=Goudet|first7=J.|last8=Ross|first8=K. G.|last9=Shoemaker|first9=D.|s2cid=28149214|title=Global Invasion History of the Fire Ant ''Solenopsis invicta'' |journal=Science|date=24 February 2011|volume=331|issue=6020|pages=1066–1068|doi=10.1126/science.1198734|pmid=21350177|bibcode=2011Sci...331.1066A|url=http://era.daf.qld.gov.au/id/eprint/6693/ }}</ref> The RIFA was believed to have been accidentally introduced to these countries via shipping crates, particularly in the case of Australia.<ref name=":5">{{cite news |last1=Murphy |first1=Damien |date=13 December 2014 |title=Red fire ants will make thongs a thing of the past |url=https://www.smh.com.au/nsw/red-fire-ants-will-make-thongs-a-thing-of-the-past-20141212-1247ze.html |access-date=30 December 2014 |work=[[Sydney Morning Herald]]}}</ref>

In Australia, RIFA ants were first identified in the [[Port of Brisbane]] in 2001, although a strategic review of the Australian RIFA eradication program published in 2021 suggested that RIFA ants may have been present but undetected in Australia as early as 1992.<ref name=":5" /><ref name=":6">{{Cite news |last=Dumas |first=Daisy |date=2023-11-28 |title=What are fire ants, and what will happen if these tiny killers take hold across Australia? |url=https://www.theguardian.com/environment/2023/nov/29/fire-ants-found-nsw-invasive-species-bites-sting-death |access-date=2024-11-14 |work=The Guardian |language=en-GB |issn=0261-3077}}</ref><ref name=":7">[https://www.agriculture.gov.au/sites/default/files/documents/Strategic%20Review%20of%20the%20National%20Red%20Imported%20Fire%20Ant%20Eradication%20Program%20August%202021.pdf Strategic Review of the National Red Imported Fire Ant Eradication Program] August 2021; National Red Imported Fire Ant Eradication Program (NRIFAEP). agriculture.gov.au</ref> As of November 2023, the invasion of fire ants is restricted to an area of 7000 km2 in [[South East Queensland]] that includes [[Brisbane]], with the colonised area bordering the state of [[New South Wales]] (NSW), with incursions reported in northern NSW on a regular basis.<ref>{{cite news |last1=Condon |first1=Matthew |date=27 July 2013 |title=Queensland launched a war against the fire ant invasion, but 12 years later, they're still on the march |url=https://www.couriermail.com.au/news/queensland/queensland-launched-a-war-against-the-fire-ant-invasion-but-12-years-later-they8217re-still-on-the-march/story-fnihsrf2-1226686256021 |access-date=30 December 2014 |work=The Courier Mail}}</ref><ref name=":6" /> Outside of this region, as of 2023, there have been seven other incursions that have had to be eradicated, with all incursions linked to ports and airports, including in [[Gladstone, Queensland|Gladstone]], the Port of Botany near [[Sydney]] (in 2014), and the Port of [[Fremantle]], [[Western Australia]].<ref name=":6" /><ref>{{cite news|title='Aggressive' red ants found at Sydney port|url=https://www.theaustralian.com.au/news/latest-news/aggressive-red-ants-found-at-sydney-port/story-fn3dxiwe-1227148994584?nk=7c72703f356c5bfeef2d137b25f72b11|access-date=30 December 2014|work=The Australian|publisher=[[Australian Associated Press]]|date=8 December 2014}}</ref> Elsewhere, fire ants have been frequently intercepted on incoming cargo in ports and airports across Australia.<ref>{{Cite web |title=Red Imported Fire Ants (Solenopsis invicta) - Response to Red imported fire ant outbreak in Australia. This includes where it has been detected, restrictions in place, actions you must take, and resources to help you manage risks. |url=https://www.outbreak.gov.au/current-outbreaks/red-imported-fire-ant |website=Outbreak.gov.au |publisher=Australian Govt.}}</ref> Of particular concern, Australian researchers predict that the entire country is able to provide suitable habitat for RIFA colonization, with the exception of highland Tasmania and the Snowy Mountains.<ref name=":7" /> In the 21-year time period between 2001 and 2022, the commonwealth and state governments of Australia spent a combined AU$644m in their attempts to eradicate RIFA ants. In 2015, the Australian National Red Imported Fire Ant Eradication Program (NRIFAEP) National Fire Ant Eradication Program was set up and received AU$411m of funding. For the time period of 2023-2027, funding of AU$593m has been agreed. Despite the funded plan and a degree of success in the eradication of RIFA not seen elsewhere in the world, some Australian experts warn that the government on a national and state level may be moving too slowly given the size of the threat.<ref name=":6" />

They were believed to be in the Philippines, but they are most likely to be misidentified for ''Solenopsis geminata'' ants.<ref>{{cite journal |last=Wetterer | first=James K. | title=Exotic spread of ''Solenopsis invicta'' (Hymenoptera: Formicidae) beyond North America | journal=[[Sociobiology]] | volume=60 | year=2013 | pages=53–63 | doi=10.13102/sociobiology.v60i1.50-55| doi-access=free }}</ref>

In the US, the [[Food and Drug Administration|FDA]] estimates that more than US$5&nbsp;billion is spent annually on medical treatment, damage, and control in RIFA-infested areas. Furthermore, the ants cause approximately $750&nbsp;million in damage annually to agricultural assets, including [[veterinarian]] bills and [[livestock]] loss, as well as [[crop]] loss.<ref>{{cite journal |last=McDonald | first=Maggie | title=Reds Under Your Feet (interview with Robert Vander Meer) | journal=[[New Scientist]] | volume=189 | issue=2538 |date=February 2006 | page=50 | url=https://www.newscientist.com/channel/opinion/mg18925381.700-interview-extinguishing-red-fire-ants.html }}</ref> Over 40 million people live in RIFA-infested areas in the southeastern United States.<ref>{{cite journal|last1=Solley|first1=GO|last2=Vanderwoude|first2=C|last3=Knight|first3=GK|title=Anaphylaxis due to Red Imported Fire Ant sting |journal=The Medical Journal of Australia|date=3 June 2002|volume=176|issue=11|pages=521–3|pmid=12064982|url=https://www.mja.com.au/journal/2002/176/11/anaphylaxis-due-red-imported-fire-ant-sting|access-date=30 December 2014|doi=10.5694/j.1326-5377.2002.tb04548.x|s2cid=33650493}}</ref> It is estimated that 30–60% of the people living in fire ant-infested areas of the US are stung each year.<ref>{{cite tech report|last1=Oi|first1=David H.|series=Public health significance of Urban Pests|url=https://www.euro.who.int/__data/assets/pdf_file/0011/98426/E91435.pdf |institution=[[World Health Organization]]|title=Pharaoh ants and fire ants|access-date=30 December 2014|pages=175|date=25 June 2008|archive-date=22 February 2017|archive-url=https://web.archive.org/web/20170222111554/https://www.euro.who.int/__data/assets/pdf_file/0011/98426/E91435.pdf|url-status=dead}}</ref> RIFA are currently found mainly in warmer US states in the south-east of the country including Florida, Georgia, South Carolina, Louisiana, Mississippi and Alabama, but extend to include parts of North Carolina, Virginia, Tennessee, Arkansas, Texas, Oklahoma, New Mexico, and California.<ref>{{Cite web |url=https://www.aphis.usda.gov/plant-pests-diseases/ifa |archive-url=https://web.archive.org/web/20240331201553/https://www.aphis.usda.gov/plant-pests-diseases/ifa |url-status=dead |archive-date=March 31, 2024 |title=Imported Fire Ants |access-date=2024-10-17 |publisher=[[USDA]]|website=Animal and Plant Health Inspection Service|date=2024-10-01}}</ref>

Since September 2004, Taiwan has been seriously affected by the red fire ant. The US, Taiwan and Australia all have ongoing national programs to control or eradicate the species, but with the exception of those in Australia, none have been especially effective. According to a study published in 2009, it took only seventy years for the [[eastern fence lizard|lizards]] in parts of the United States to adapt to the ant's presence; they now have longer legs and new behaviors that aid them in escaping from the danger.<ref>{{cite news|last1=Bryner|first1=Jeanna|title=Lizards' Dance Avoids Deadly Ants|url=https://www.livescience.com/7655-lizards-dance-avoids-deadly-ants.html|access-date=30 December 2014|work=Live Science|date=26 January 2009}}</ref>

''[[Solenopsis invicta]]'' is the most famous species in this genus, especially in the US, however several other species are similarly dangerous and invasive, such as ''[[Solenopsis geminata]]'', which has invaded most of the tropical countries, wreaking havoc in medical systems especially in unprepared countries and islands.<ref name="Hoffmann">{{cite journal |last1=Hoffmann |first1=Benjamin D |last2=Ducarme |first2=Frédéric |last3=Bradford |first3=DanaKai |last4=Martinez |first4=Santiago  |date=2023 |title=Spread of stinging ants to oceanic islands, and the need to raise awareness of prevention and treatment of ant stings |journal=Emergency Medicine Australasia |volume= 35|issue= 4|pages= 560–563|doi=10.1111/1742-6723.14165 |pmid=36596650 |s2cid=255469772 |doi-access=free }}</ref>

== Sting symptoms and treatment ==
[[Image:FireAntBite.jpg|thumb|150px|A human leg three days after brief contact with a fire ant colony|alt=Human leg three days after brief contact with fire ant colony]]
The venom of fire ants is mainly (>95%) composed of oily [[alkaloid]]s structurally derived from [[piperidine]] (also known as [[solenopsin]]s) mixed with a small amount of toxic proteins.<ref name=":3">{{Citation|last=Fox|first=Eduardo Gonçalves Paterson|title=Venom Toxins of Fire Ants|date=2014|url=https://link.springer.com/referenceworkentry/10.1007/978-94-007-6649-5_38-1|work=Venom Genomics and Proteomics|pages=1–16|publisher=Springer, Dordrecht|doi=10.1007/978-94-007-6649-5_38-1|isbn=9789400766495|access-date=2018-12-07|url-access=subscription}}</ref><ref>{{Cite journal|last1=dos Santos Pinto|first1=José R. A.|last2=Fox|first2=Eduardo G. P.|last3=Saidemberg|first3=Daniel M.|last4=Santos|first4=Lucilene D.|last5=da Silva Menegasso|first5=Anally R.|last6=Costa-Manso|first6=Eliúde|last7=Machado|first7=Ednildo A.|last8=Bueno|first8=Odair C.|last9=Palma|first9=Mario S.|date=2012-09-07|title=Proteomic View of the Venom from the Fire Ant Solenopsis invicta Buren|journal=Journal of Proteome Research|volume=11|issue=9|pages=4643–4653|doi=10.1021/pr300451g|pmid=22881118|issn=1535-3893}}</ref> Fire ant stings are painful, characterised by a local burning sensation, followed by [[urticaria]].<ref name=":3" /> The sting site typically swells into a bump within hours, which can cause further pain and irritation, especially following several stings at the same place. The bump may develop into a white [[pustule]] within 24–36 hours which can become infected if scratched, but will spontaneously flatten within a few days if left alone. The pustules are obtrusive and uncomfortable while active and, if they become infected, may cause scarring.<ref>{{cite journal|vauthors=deShazo RD, Butcher BT, Banks WA|year=1990|title=Reactions to the stings of the imported fire ant|journal=New England Journal of Medicine|volume=323|issue=7|pages=462–6|doi=10.1056/NEJM199008163230707|pmid=2197555}}</ref> Some people may become allergic to the venom,<ref name=":4" /> and if untreated, may become increasingly sensitive to the point of experiencing [[anaphylaxis]] following fire ant stings, which requires emergency treatment.<ref name="Hoffmann" /> Management of an emergency visit due to anaphylaxis is recommended with the use of [[Epinephrine|adrenaline]].<ref>{{cite journal|last1=Lee|first1=Jason|last2=Betschel|first2=Stephen|title=A case of the first documented fire ant anaphylaxis in Canada|journal=Allergy, Asthma & Clinical Immunology|date=2013|volume=9|issue=1|pages=25|doi=10.1186/1710-1492-9-25|pmid=23837799|pmc=3711928 |doi-access=free }}</ref><ref name="Hoffmann" /> It has been demonstrated that, whilst pustule formation results from the injected venom alkaloids,<ref>{{Cite journal|date=1993-01-01|title=Effects of fire ant venom alkaloids on platelet and neutrophil function|journal=Life Sciences|volume=53|issue=14|pages=1105–1112|doi=10.1016/0024-3205(93)90546-F|pmid=8396703|issn=0024-3205|last1=Javors|first1=M.A.|last2=Zhou|first2=W.|last3=Maas|first3=J.W.|last4=Han|first4=S.|last5=Keenan|first5=R.W.}}</ref> allergy to fire ant stings is caused solely by venom [[allergen]]ic proteins.<ref name=":4">{{Cite journal|last1=Diaz|first1=Bruno L.|last2=Machado|first2=Ednildo A.|last3=Atella|first3=Georgia C.|last4=Araujo|first4=Maria F. C.|last5=Araujo|first5=Almair Ferreira de|last6=Poublan|first6=Luiz E.|last7=Gama|first7=Diogo|last8=Monteiro|first8=Ana Paula|last9=Fox|first9=Eduardo G. P.|date=2018-09-26|title=The allergic response mediated by fire ant venom proteins|journal=Scientific Reports|volume=8|issue=1|pages=14427|doi=10.1038/s41598-018-32327-z|issn=2045-2322|pmc=6158280|pmid=30258210|bibcode=2018NatSR...814427Z}}</ref>

First aid for fire ant stings includes external treatments and oral medicines. There are also many [[home remedies]] of varying efficacy, including immediate application of a solution of half bleach and half water, or [[aloe vera]] gel – the latter of which is also often included in [[over-the-counter]] creams that also include medically tested and verified treatments.<ref name=consideration/> External, [[topical]] treatments include the anesthetic [[benzocaine]], the [[antihistamine]] [[diphenhydramine]], and the [[corticosteroid]] [[hydrocortisone]].<ref name=consideration/> Antihistamines or topical corticosteroids may help reduce the itching and will generally benefit local sting reactions.<ref>{{cite book|last1=Talcott|first1=Patricia A.|last2=Peterson|first2=Michael E.|title=Small animal toxicology|date=2013|publisher=Elsevier|location=St. Louis, Mo.|isbn=978-1455707171|pages=584–585|edition=3rd|url=https://books.google.com/books?id=BLkPFlB15v0C&q=Antihistamines+or+topical+corticosteroids+and+fire+ants&pg=PA585|access-date=30 December 2014}}</ref> Oral medicine includes antihistamines.<ref>{{cite web|title=Fire Ant Bites|url=https://www.aocd.org/?page=FireAntBites|publisher=American Osteopathic College of Dermatology|access-date=30 December 2014}}</ref> Severe allergic reactions to fire ant stings, including severe chest pain, nausea, severe sweating, loss of breath, serious swelling, and slurred speech<ref>{{cite web |url=https://www.cdc.gov/niosh/topics/insects/ |title=Insects and Scorpions |access-date=11 April 2008 |date=22 October 2008 |publisher=Centers for Disease Control and Prevention and The National Institute for Occupational Safety and Health}}</ref> can be fatal if not treated.<ref>{{cite journal|last1=Prahlow|first1=JA|last2=Barnard|first2=JJ|s2cid=39162329|title=Fatal anaphylaxis due to fire ant stings |journal=The American Journal of Forensic Medicine and Pathology|date=June 1998|volume=19|issue=2|pages=137–42|pmid=9662108|doi=10.1097/00000433-199806000-00007}}</ref><ref name="Hoffmann" />

== Predators ==
[[File:Dionaea muscipula trap.jpg|thumb|[[Venus flytrap]]]]
[[File:Drosera anglica ne1.JPG|thumb|A species of ''[[Drosera]]'' with its sticky leaves that trap many ants|alt=Drosera with sticky leaves]]
[[File:Phorid fly2.jpg|thumb|left|''[[Pseudacteon|Pseudacteon curvatus]]'', phorid fly parasitoid of fire ants|alt=Phorid fly parasitoid of fire ants]]
Phorid flies, or [[Phoridae]], are a large family of small, hump-backed flies somewhat smaller than [[Drosophilidae|vinegar flies]]; two species in this family (''[[Pseudacteon tricuspis]]'' and ''[[Pseudacteon curvatus]]'') are [[parasitoid]]s of the [[red imported fire ant]] in its native range in [[South America]]. Some 110 species of the genus ''[[Pseudacteon]]'', or ant-decapitating flies, have been described. Members of ''Pseudacteon'' reproduce by laying eggs in the thorax of the ant. The first [[instar]] larvae migrates to the head, then develops by feeding on the [[hemolymph]], muscle tissue, and nervous tissue. After about two weeks, they cause the ant's head to fall off by releasing an [[enzyme]] that dissolves the membrane attaching the ant's head to its body. The fly pupates in the detached head capsule, emerging two weeks later.<ref name=Venom>{{cite news|last1=Ehrenberg|first1=Rachel|title=Venom attracts decapitating flies|url=https://www.sciencenews.org/article/venom-attracts-decapitating-flies|access-date=30 December 2014|work=[[Science News]]|date=18 September 2009}}</ref>

''Pseudacteon'' flies appear to be important ecological constraints on ''Solenopsis'' species and they have been introduced throughout the southern United States, starting with [[Travis County, Texas|Travis]], [[Brazos County, Texas|Brazos]], and [[Dallas County, Texas|Dallas]] counties in Texas, as well as south central [[Alabama]], where the ants first entered North America.<ref>{{cite journal|last1=Porter|first1=Sanford D.|last2=Graham|first2=L. C. “Fudd”|last3=Johnson|first3=Seth J.|last4=Thead|first4=Larry G.|last5=Briano|first5=Juan A.|title=The Large Decapitating Fly (Diptera: Phoridae): Successfully Established on Fire Ant Populations in Alabama|journal=Florida Entomologist|date=June 2011|volume=94|issue=2|pages=208–213|doi=10.1653/024.094.0213|doi-access=free}}</ref>

The [[Venus flytrap]], a carnivorous plant, is native only to North and South Carolina in the United States. About 33% of the prey of the Venus flytrap are ants of various species.<ref name=Ellison>{{cite journal | doi=10.1093/jxb/ern179 | last1=Ellison |first1=DM|last2= Gotelli |first2= NJ | title=Energetics and the evolution of carnivorous plants—Darwin's 'Most Wonderful plants in the world' | journal=Journal of Experimental Botany | volume=60 | year=2009 | issue=1 | pages=19–42 | pmid=19213724 | doi-access=free }}</ref> They lure their prey with a sweet sap. Once the prey has entered the trap and within about three seconds of touching two or three "trigger hairs" on the surface of the trap, the leaf closes around the prey and digests it. The majority of ants that are captured include non-native RIFAs, and three other species of ants.<ref name=Ellison/> Other carnivorous plants, such as sundews (''[[Drosera]]'') and various kinds of [[pitcher plant]]s also trap many ants.

Key natural enemies of fire ants also include other ant species which will attack prospective queens during the nest founding period, when there is an absence of workers to defend the emergent colony.<ref>{{Cite journal|last1=Greenberg|first1=Les|last2=Kabashima|first2=John N.|last3=Allison|first3=Clinton J.|last4=Rust|first4=Michael K.|last5=Klotz|first5=John H.|last6=Hurvois|first6=Jean-Pierre|last7=Paine|first7=Timothy D.|date=2008-11-01|title=Lethality of Red Imported Fire Ant Venom to Argentine Ants and Other Ant Species|journal=Annals of the Entomological Society of America|volume=101|issue=6|pages=1162–1168|doi=10.1603/0013-8746-101.6.1162|s2cid=83922482|issn=0013-8746}}</ref> Frequent competitors of fire ant founding queens include other ''Solenopsis'' [[thief ant]] species, and some invasive pest species, such as the [[Rasberry crazy ant|tawny crazy ant]], and the black [[Crazy Ant|crazy ant]].<ref name=":2" />

A number of [[entomopathogenic fungi]] are also natural enemies of fire ants, such as ''[[Beauveria bassiana]]''<ref>{{Cite journal|last1=Siebeneicher|first1=Stacy R.|last2=Bradleigh^Vinson|first2=S.|last3=Kenerley|first3=Charles M.|date=1992-05-01|title=Infection of the red imported fire ant by Beauveria bassiana through various routes of exposure|journal=Journal of Invertebrate Pathology|volume=59|issue=3|pages=280–285|doi=10.1016/0022-2011(92)90133-O|bibcode=1992JInvP..59..280S |issn=0022-2011}}</ref> and ''[[Metarhizium anisopliae]]''<ref>{{Cite journal|last1=Angelone|first1=Steven|last2=Bidochka|first2=Michael J.|date=2018-07-01|title=Diversity and abundance of entomopathogenic fungi at ant colonies|journal=Journal of Invertebrate Pathology|volume=156|pages=73–76|doi=10.1016/j.jip.2018.07.009|pmid=30017951|bibcode=2018JInvP.156...73A |s2cid=51677575|issn=0022-2011}}</ref>''.'' The latter is commercially available for the biological control (as an alternative to conventional pesticides) of various pest insects, and a new proposed technology has increased its shelf life and efficiency against fire ants.<ref>{{Cite journal|last1=Qiu|first1=Hua-Long|last2=Fox|first2=Eduardo G. P.|last3=Qin|first3=Chang-Sheng|last4=Zhao|first4=Dan-Yang|last5=Yang|first5=Hua|last6=Xu|first6=Jin-Zhu|date=2019-07-01|title=Microcapsuled entomopathogenic fungus against fire ants, Solenopsis invicta|journal=Biological Control|volume=134|pages=141–149|doi=10.1016/j.biocontrol.2019.03.018|bibcode=2019BiolC.134..141Q |s2cid=132021733|issn=1049-9644}}</ref>

==Species==
{{main|List of Solenopsis species}}
The genus ''Solenopsis'' contains over 200 species.<ref name="AntCat"/> Not all species included in the genus are known as fire ants, but most are small slow-moving ants which are unable to sting, called [[thief ant]]s. "True" fire ants are but a group of about 20 species of ''Solenopsis'' which are larger, and will viciously sting in swarms whenever disturbed.<ref>{{Cite journal|last1=Pitts|first1=James P.|last2=Camacho|first2=Gabriela P.|last3=Gotzek|first3=Dietrich|last4=Mchugh|first4=Joseph V.|last5=Ross|first5=Kenneth G.|date=April 2018|title=Revision of the Fire Ants of the Solenopsis saevissima Species-Group (Hymenoptera: Formicidae)|journal=Proceedings of the Entomological Society of Washington|volume=120|issue=2|pages=308–411|doi=10.4289/0013-8797.120.2.308|s2cid=91162352|issn=0013-8797}}</ref> Some of the most studied species include:
{{div col|colwidth=30em}}
* ''[[Red imported fire ant|Solenopsis invicta]]'' <small>Buren, 1972</small>
* ''[[Black imported fire ant|Solenopsis richteri]]'' <small>Forel, 1909</small>
* ''[[Solenopsis geminata]]'' <small> (Fabricius, 1804) </small>
* ''[[Solenopsis saevissima]]'' <small>(Smith, 1855)</small>
* ''[[Solenopsis silvestrii]]'' <small>Emery, 1906</small>
* ''[[Solenopsis solenopsidis]]'' <small>(Kusnezov, 1953)</small>
* ''[[Southern fire ant|Solenopsis xyloni]]'' <small>McCook, 1879</small>
{{div col end}}

== See also ==
* [[Ant venom]]
* [[Ants of medical importance]]
* [[Paraponera clavata|Bullet ant]]
* [[Bulldog ant]]
* [[Red imported fire ants in Australia]]

== References ==
{{Reflist|30em}}

== Further reading ==
* {{cite book
| author = [[Bert Hölldobler]] and [[Edward O. Wilson]]
| title = The Ants
| publisher = Belknap Press of Harvard University Press
| location = Cambridge
| year = 1990
| isbn = 978-3-540-52092-4
}}

== External links ==
* {{Commons-inline|italic=1}}
* {{Wikispecies-inline|Solenopsis|''Solenopsis''}}

{{Taxonbar|from=Q1075697}}

[[Category:Insects of Central America]]
[[Category:Solenopsis (ant)]]
<!-- [[Category:Pest insects]] moved to "Red imported fire ant" -->