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Citrus Pests


Argentine ant


Scientific name


Linepithema humile (Hymenoptera: Formicidae)

Similar species


Other Linepithema species, particularly L. oblongum from Argentina and Bolivia

Flat-backed tyrant ants, Iridomyrmex anceps group

Odorous house ant, Tapinoma sessile
The Argentine ant can be distinguished from the odorous house ant by crushing and smelling the workers' remains. Argentine ants have a stale musty odor while the odorous house ant smells like rotten coconuts.



United States: Alabama, California, Florida, Georgia, Hawaii, Kentucky, Mississippi, Nevada, New Mexico, North Carolina, Oklahoma, Oregon, South Carolina, Tennessee, and Texas.

Worldwide: Australia, Central and South America, South Africa, southern Europe, and New Zealand.

Native to Argentina, Brazil, Paraguay, and Uruguay.

Diagnostic characteristics

  • The nests are not easily identifiable and can be found around bricks, boards, rotting wood, refuse piles, bark crevices, stumps, bee hives, and bird nests.
  • During environmental stress such as drought, the ants may invade homes or other structures to establish a nest.
  • Prefer to nest in moist leaf litter or organic mulch.
  • Adult length varies: female workers (1.7 mm, 0.07 in); males (2.5 mm, 0.1 in), and queens (4 - 6 mm, 0.2 in).
  • Usually reddish or yellowish body and appendages, but brick-red to dark brown are also known.
  • Smooth and hairless on the top of the head and thorax.
  • Wings are present briefly in unmated, reproductive individuals. Four, white to yellowish wings with dark brown veins on both males and females. The wings of males have a stigma (small, colored area near the wing tip).
  • Hinged or bent antennae (geniculate) with 12 segments.
  • One segmented area between thorax and abdomen (petiole).
  • Females are 2 mm (0.09 in.) in length; males are 3 mm (0.12 in.) in length.
  • White with two black eyespots.
  • Four larval instars.
  • Females are 1.7 mm (0.07 in.) in length, males are 2.5 mm(0.1 in.) in length.
  • White to cream-colored.
  • Immobile, cared for by workers.
  • 0.30 mm (0.01 in.) in length and 0.20 mm (0.00 8in.) in width.
  • Translucent.
  • Ovoid.



Argentine ants do not attack citrus directly but impact citrus cultivation by preventing effective use of biological controls, killing pollinators, and plugging irrigation lines.

Host damage

  • Rarely damage citrus or crops directly.
  • Protect honeydew-producing insects, interfering with the biological control of scales, whiteflies, and aphids.
  • Particularly problematic in monoculture citrus and grape orchards.
  • Can destroy beehives.
  • Plug irrigation systems.



Argentine ants can occur in very high densities in citrus orchards and other human-modified agricultural systems. Because the Argentine ant lacks aggression among other colonies of the same species, different colonies can work cooperatively, developing a very large "supercolony."

Worker ants are very fast moving. They are also highly aggressive and can out-compete other ant species for resources. The Argentine ant is a serious pest of commercial beekeeping operations. They have been known to overtake one to two hives a day.



Synonyms of the Argentine ant include Iridomyrmex humilis (Mayr).



California Academy of Sciences. 2010. AntWeb database - Species: Linepithema humile.(

Daugherty, M., and K. Hung. 2009. Argentine ant (Linepithema humile). Center for Invasive Species Research, University of California, Riverside. (

Jayasimha, P. 2009. Nest biology and structure of Argentine ants. (

Krushelnycky, P., and A. Suarez. 2009. Global invasive species database: Linepithema humile. (

Layton, B., and J.A. MacGown. 2006. Control of Argentine ants and odorous house ants in the home. Mississippi State University Extension Service, Publication 2407. (

Roura-Pascual, N., A.V. Suarez, C. Gomez, P. Pons, Y. Touyama, A.L. Wild, and T. Peterson. 2004. Geographical potential of Argentine ants (Linepithema humile Mayr) in the face of global climate change. Proc. R. Soc. B 271: 2527-2535.

Walker, K. 2006. Argentine ant (Linepithema humile): Pest and Diseases Image Library. (

Westervelt, D., and E.T. Jameson. 2009. Pest alert - Argentine ant, Liniepithema humile Mayr (Hymenoptera: Formicidae). (

Wild, A. L. 2004. Taxonomy and distribution of the Argentine ant, Linepithema humile (Hymenoptera: Formicidae). Ann. Entomol. Soc. Am. 97: 1204-1215. (



Martin, K.W., J.A. Weeks, A.C. Hodges, and N.C. Leppla


Citrus Pests
Content last updated June, 2012