Rasberry crazy ant

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Nylanderia fulva
Tawny crazy ant (Nylanderia fulva) female worker.jpg
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Genus: Nylanderia
N. fulva
Binomial name
Nylanderia fulva
Mayr 1862[1]

Prenolepis fulva

The tawny crazy ant[2][3][4] or Rasberry crazy ant,[2] Nylanderia fulva, is an ant originating in South America. Like the longhorn crazy ant (Paratrechina longicornis), this species is called "crazy ant" because of its quick, unpredictable movements (the related N. pubens is known as the "Caribbean crazy ant"). It is sometimes called the "Rasberry crazy ant" in Texas after the exterminator Tom Rasberry, who noticed that the ants were increasing in numbers in 2002.[5][6] Scientists have reorganised the genera taxonomy within this clade of ants, and now it is identified as Nylanderia fulva.[7]

In 2014, it was discovered that the ant produces and covers itself with formic acid as an antidote to the fire ant's venom.[8] It is the first known example of an insect being able to neutralize another insect's venom, an ability speculated to have evolved in South America where the two species share the same native range. Colonies have multiple queens, which also contributes to their survival.[9]

As of 2012, the ants have established colonies[3][4] in all states of the Gulf Coast of the United States including at least 27 counties in Southeast Texas.[citation needed]


The ant is about 3 mm (or about 1/8 inches) long, thus smaller than the red imported fire ant, Solenopsis invicta. It is covered with reddish-brown hairs. Their larvae are plump, and hairy, with a specific conformation of mouthparts and unique mandible morphology that allows for precise species identification.[10] The colonies live under stones or piles; they have no centralized nests, beds, or mounds.[2] They tend aphids for honeydew, feed on small insects and vertebrates, and forage on plants, especially for sweet materials. The ants appear to prefer the warmth and moisture of the coast.[11]

N. fulva has been a pest in rural and urban areas of Colombia, South America, where it displaced all other ant species. There, small poultry such as chickens have died of asphyxiation while larger animals, such as cattle, have been attacked around the eyes, nostrils, and hooves. Grasslands have dried out because of the increase in plant-sucking insect pests (hemipterans), which the ants cultivate to feed on the sugary "honeydew" that they excrete.[2]

When attacked, these ants, like other formicine ants, can bite but not sting, and excrete formic acid through a hairy circle or acidopore on the end of the abdomen, using it as a venom,[12] which causes a minute pain that quickly fades. Formic acid was named after the Latin word formica (ant), because it was first distilled from ants in the 17th century.[13] Uniquely, the tawny ant also uses formic acid as an antidote against the venom alkaloids of the fire ant (known as solenopsins). The venom alkaloids of fire ants have been demonstrated to be strongly paralytic against competitor species,[14] thus the tawny crazy ant may have developed a resistance by acid-immobilisation of the venom toxins.

Tawny crazy ants were found to displace other ant species in their native Argentina and later the US, including the red imported fire ant.[6] This was first thought to be due to exploitative and interference competition.[15]

Formic acid as an antidote to fire ant venom[edit]

In March 2014, researchers concluded that formic acid helped tawny crazy ants survive fire ant venom in ant fights 98% of the time; when the gland ducts were blocked with nail polish in an experiment, crazy ants had only a 48% chance of surviving fights with fire ants.[8] After exposure to fire ant venom, N. fulva retreats, covers itself with formic acid[16] and returns to the fight.[8] This is the first known example of an insect detoxifying another insect's venom, and the first discovery of an ionic liquid in nature which results from mixing of formic acid with venom from S. invicta.

How formic acid acts as an antidote against the much more toxic fire ant's venom is unknown. Fire ant venom is a mixture of toxic alkaloids and proteins that presumably enable the alkaloids to enter rival ants’ cells.[13] Each alkaloid in the fire ant's venom, including solenopsin, has a six-membered heterocyclic ring with fat-soluble side chains.[13] The researchers who discovered the antidote property of formic acid in crazy ants speculate that the formic acid denatures the proteins in fire ant venom.[8] Another possibility is that the nitrogen on an alkaloid's heterocyclic ring is protonated, rendering the ionic molecule less lipophilic, thus less likely to penetrate the tawny crazy ant's cells.[13]


N. fulva eats liquids,[3][4] including plant nectar[3][4] and insect honeydew.[3][4][17] Calcium, sodium, and potassium are very important to N. fulva: Higher environmental potassium decreased abundance, and higher potassium + sodium decreased abundance even more so.[3][4] Meanwhile, higher calcium increased abundance.[3][4]

Attraction to electrical equipment[edit]

Infestations of Nylanderia fulva in electrical equipment can cause short circuits, sometimes because the ants chew through insulation and wiring.[3] Overheating, corrosion, and mechanical failures also result from accumulations of dead ants and nest detritus in electrical devices.[18] If an ant is electrocuted, it can release an alarm pheromone in dying, which causes other ants to rush over and search for attackers. If a large enough number of ants gathers, it may short out systems.[19]

It is unclear why colonies of Nylanderia fulva are attracted to electrical equipment.[6][20] They may sense the magnetic fields that surround wires conducting electric current, or they may prefer the warmth produced by resistance to the currents in the wires. Some argue they simply are searching for food or an attractive place to nest.[21]

Rate of spread[edit]

The Texas A&M University research extension service quotes the annual rate of spread by ground migration as about 240 and 360 m per year in neighborhoods and industrial areas, respectively, and 207 m/year in rural landscapes[22] hence spreading more slowly than fire ants.[16] Other sources quote 800 m (0.50 mi) per year.[6] Being carried by people, animals, and vehicles (in trash for example), the observed rate is much higher: the spread from five Texas counties in 2002 to 20 in 2007 yields an accelerated rate of 8 km (5.0 mi) per year, at which rate it would take about 70 years for them to reach New Orleans. However, in 2011, tawny crazy ants were reported in Mississippi,[23] in August 2012 in Port Allen, Louisiana,[24] and in 2013 in Georgia.[25]

Range in the United States[edit]

Reported distribution of the Rasberry crazy ant in the United States (2012); actual occurrence is thought to be more widespread

The earliest record of N. fulva presence in the US is from Brownsville, Texas, in 1938.[26] By the early 2000s, the ants spread across the southeastern portion of Texas[7] including at more than 27 counties[22] Large population explosions have been described also on St Croix in the US Virgin Islands; in many cases the ant species was misidentified as its close relative, the hairy crazy ant, Nylanderia pubens.[5][27][28][29] As of 2012, the ants have established colonies in all states of the Gulf Coast of the United States.[6][7] The ant is considered an invasive species.[2] As of 2021 N. fulva establishment is limited to some southern parts of the country.[3]

Control in the US[edit]

The ants are not attracted to ordinary ant baits, and are not controlled by over-the-counter pesticides,[6][30] and are harder to fully exterminate than many other species because their colonies have multiple queens.[9] In June 2008, the United States Environmental Protection Agency granted temporary approval for the use of fipronil, an antitermite agent, to control this ant.[31] Its use is currently restricted to infested counties.[32]

In 2015, the microsporidian parasite Myrmecomorba nylanderiae was found to be a pathogen of the tawny crazy ant.[33][34] In March 2022, further research indicated that this unicellular fungus may be an effective biological control for the tawny ant.[35][36]

See also[edit]


  1. ^ Mayr, G. 1862. Myrmecologische Studien.[dead link] Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 12:649-776.
  2. ^ a b c d e "Tawny (Rasberry) Crazy Ant. Nylanderia fulva". Texas A&M, Department of Entomology, Center for Urban & StructuralEntomology. Retrieved 2013-05-21.
  3. ^ a b c d e f g h i Reihart, Ryan (2021-01-21). "Invasive tawny crazy ants have an intense craving for calcium – with implications for their spread in the US". The Conversation. Retrieved 2021-01-23.
  4. ^ a b c d e f g Reihart, Ryan W.; Angelos, Kiersten P.; Gawkins, Kaitlin M.; Hurst, Shania E.; Montelongo, Denise C.; Laws, Angela N.; Pennings, Steven C.; Prather, Chelse M. (2021-01-11). "Crazy ants craving calcium: macronutrients and micronutrients can limit and stress an invaded grassland brown food web". Ecology. Wiley. 102 (2): e03263. doi:10.1002/ecy.3263. ISSN 0012-9658. PMID 33314072. S2CID 229178510.
  5. ^ a b Ayres, Chris (2008-05-16). "Billions of electronic-eating 'crazy Rasberry ants' invade Texas". Times UK.
  6. ^ a b c d e f Main, Douglas (17 May 2013). "'Crazy' Ants Driving Out Fire Ants in Southeast". LiveScience.com. Retrieved 2013-05-18.
  7. ^ a b c Gotzek, D.; Brady, S. N. G.; Kallal, R. J.; Lapolla, J. S. (2012). Moreau, Corrie S (ed.). "The Importance of Using Multiple Approaches for Identifying Emerging Invasive Species: The Case of the Rasberry Crazy Ant in the United States". PLOS ONE. 7 (9): e45314. Bibcode:2012PLoSO...745314G. doi:10.1371/journal.pone.0045314. PMC 3462614. PMID 23056657.
  8. ^ a b c d LeBrun, Edward G.; Nathan T. Jones; Lawrence E. Gilber (28 February 2014). "Chemical Warfare Among Invaders: A Detoxification Interaction Facilitates an Ant Invasion". Science. 343 (6174): 1014–1017. Bibcode:2014Sci...343.1014L. doi:10.1126/science.1245833. PMID 24526314. S2CID 45087292.
  9. ^ a b Can Ants Eat Your Computer: Why the "crazy rasberry" ant infests electronic devices., Slate, 20 May 2008.
  10. ^ Correa Bueno, Odair; Rossi, Monica Lanzoni; Solis, Daniel Russ; Fox, Eduardo Gonçalves Paterson (2018-01-02). "Morphological Studies on the Mature Worker Larvae of Paratrechina fulva (Hymenoptera, Formicidae)". doi:10.6084/m9.figshare.5746644.v1. {{cite journal}}: Cite journal requires |journal= (help)
  11. ^ Ralph Blumenthal, A Pest Without a Name, Becoming Known to Ever More, The New York Times, May 16, 2008
  12. ^ Touchard, Axel; Aili, Samira; Fox, Eduardo; Escoubas, Pierre; Orivel, Jérôme; Nicholson, Graham; Dejean, Alain (2016-01-20). "The Biochemical Toxin Arsenal from Ant Venoms". Toxins. 8 (1): 30. doi:10.3390/toxins8010030. ISSN 2072-6651. PMC 4728552. PMID 26805882.
  13. ^ a b c d Everts, Sarah (3 March 2014). "An Ant's Acid Antidote". Chemical & Engineering News. 92 (9): 44–45. doi:10.1021/cen-09209-scitech3. Retrieved 29 April 2014.
  14. ^ Fox, Eduardo G.P.; Wu, Xiaoqing; Wang, Lei; Chen, Li; Lu, Yong-Yue; Xu, Yijuan (February 2019). "Queen venom isosolenopsin A delivers rapid incapacitation of fire ant competitors". Toxicon. 158: 77–83. doi:10.1016/j.toxicon.2018.11.428. PMID 30529381. S2CID 54481057.
  15. ^ Danny Lee McDonald (December 2012). "Investigation of an invasive ant species: Nylanderia fulva colony extraction, management, diet preference, fecundity, and mechanical vector potential" (PDF). aglifesciences.tamu.edu. Archived from the original (PDF) on 22 September 2013. Retrieved 19 November 2018.
  16. ^ a b University of Texas at Austin (February 13, 2014). "Crazy ants dominate fire ants by neutralizing their venom". ScienceDaily. Retrieved 16 February 2014.
  17. ^ Sharma, Shweta; Oi, David H.; Buss, Eileen A. (2013). "Honeydew-Producing Hemipterans in Florida Associated with Nylanderia fulva (Hymenoptera: Formicidae), an Invasive Crazy Ant". The Florida Entomologist. Florida Entomological Society. 96 (2): 538–547. doi:10.1653/024.096.0219. ISSN 0015-4040. S2CID 54668879.
  18. ^ NASA moves to save computers from swarming ants | Computerworld, Computerworld, 15 May 2008.
  19. ^ McConnaughey, Janet. "'Hairy crazy ants' invade from Florida to Texas - Technology & science - Science - NBCNews.com". NBC News. Retrieved 2012-08-13.
  20. ^ Opam, Kwane (26 September 2011). "These Ants Terrorize Everything—Even Gadgets". gizmodo.com. Retrieved 2 October 2011.
  21. ^ Mooallem, Jon (2013-12-05). "There's a Reason They Call Them 'Crazy Ants'". The New York Times.
  22. ^ a b "Tawny (Rasberry) Crazy Ant". University of Texas A & M University, Center for Urban and Structural Entomology. Retrieved 16 February 2014.
  23. ^ Joe A. MacGown. Tawny crazy Ants invade Mississippi. YouTube video. Posted 2011-09-29.
  24. ^ Kiran Chawla. Army of hard to kill ants marches into south Louisiana. WAFB, Port Allen, LA. Posted 2012-08-14.
  25. ^ Sharon Dowdy. Invasive tawny crazy ant found in Georgia. University of Georgia. Posted 2013-09-17.
  26. ^ http://gap.entclub.org/taxonomists/Trager/1984b.pdf[permanent dead link]
  27. ^ Wetterer, James K.; Keularts, Jozef L. W. (September 2008). "Population explosion of the hairy crazy ant, Paratrechina pubens (hymenoptera: formicidae), on St. Croix, US Virgin Islands". Florida Entomologist. 91 (3): 423–427. doi:10.1653/0015-4040(2008)91[423:peothc]2.0.co;2. S2CID 86286910.
  28. ^ Robert Lee (20 September 2013). "'Crazy Ants': The ants that destroy electronics march into Georgia". www.wsbtv.com. Archived from the original on 21 September 2013. Retrieved 15 December 2018 – via web.archive.org.
  29. ^ Arjan van den Bosch. "Ccrazy Rasberry ant". web.archive.org. Ant-maps.com. Archived from the original on 1 August 2009. Retrieved 15 December 2018.
  30. ^ Ants swarm over Houston area, fouling electronics, Yahoo News, 15 May 2008. Archived 19 May 2008 at the Wayback Machine
  31. ^ Pesticide for SE Texas 'crazy' ants approved by EPA, Houston Chronicle, 2008-07-01, retrieved 2008-07-01
  32. ^ FIFRA Sec. 18 Quarantine Exemption Use Directions, Texas Department of Agriculture, 2015, retrieved 2016-06-14
  33. ^ Plowes, RM; Becnel, JJ; LeBrun, EG; Oi, DH; Valles, SM; Jones, NT; Gilbert, LE (July 2015). "Myrmecomorba nylanderiae gen. et sp. nov., a microsporidian parasite of the tawny crazy ant Nylanderia fulva". Journal of Invertebrate Pathology. 129: 45–56. doi:10.1016/j.jip.2015.05.012. PMID 26031565.
  34. ^ Wang, Z; Moshman, L; Kraus, EC; Wilson, BE; Acharya, N; Diaz, R (15 December 2016). "A Review of the Tawny Crazy Ant, Nylanderia fulva, an Emergent Ant Invader in the Southern United States: Is Biological Control a Feasible Management Option?". Insects. 7 (4): 77. doi:10.3390/insects7040077. PMC 5198225. PMID 27983690.
  35. ^ Stokstad, Eric (28 March 2022). "Invasive crazy ants could meet their match in a mysterious, funguslike pathogen". Science. AAAS.
  36. ^ LeBrun, Edward G.; Jones, Melissa; Plowes, Robert M.; Gilbert, Lawrence E. (5 April 2022). "Pathogen-mediated natural and manipulated population collapse in an invasive social insect". Proceedings of the National Academy of Sciences. 119 (14): e2114558119. doi:10.1073/pnas.2114558119. PMC 9168452. PMID 35344435. S2CID 247778033.

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