Anoplolepis gracilipes (Smith), the yellow crazy ant, is considered to be among the top 100 most destructive invasive species in the world (Lowe et al, 2004). Its native range is unclear, although it is thought to have possibly come from West Africa. This species has spread to many other localites and is now found in Hawaii. This species has not yet been found in the continental United States, but it is one that is being closely monitored for. When introduced to new ecosystems, it sometimes causes serious problems with devastating consequences. In some localities this species forms supercolonies with multiple queens. Workers from the different colonies do not fight one another, and devastate various forms of wildlife killing animals with their formic acid.
Size approximately 4 mm. Color, yellowish-brown gaster usually slightly darker. Head and body with little sculpture, appearing smooth, shining. Antennae 11 segmented. Legs and antennae extremely long. Eyes relatively large and slightly protruding. Mandibles each with 8 teeth. Clypeus protruding medially, anterior margin convex; lacking longitudinal carinae. Alitrunk slender; pronotum narrow, promesonotal dorsum almost straight in profile. Anterior portion of mesonotal dorsum, back to the propodeum, gently concave in profile; metanotal groove lacking. Propodeum lacking spines, propodeal dorsum convex in profile. One node present; thick, with an inverted-U-shaped crest. Head and gaster with erect hairs, mesosomal dorsum lacking erect hairs. Stinger lacking; acidopore present.
yellow crazy ant, crazy ant, long-legged ant, Maldive ant, ashinaga-ki-ari (Japan), gramang ant (Indonesia)
Biology and Economic Importance
Colonies: This species is polyergerus and may form supercolonies, which may extend over large areas (10–150 ha) with densities as high as 20 million workers/ha (Harris and Berry, 2008), although individual nests average about 4000 individuals. Workers are produced throughout the year, and sexual stages may also be present year round. If disturbed, colonies readily move. Colonies may be found in a wide variety of areas such as under leaf litter, in cracks and crevices in the soil, in various animal burrows, in tree hollows, under and in urban structures, and in debris.
Foraging: Anoplolepis gracilipes forages on and above ground both diurnally and nocturnally. Foraging may occur over a wide range of temperatures, although extremely hot or cool temperature inhabit foraging activities. This species discovers food rapidly, even faster than Paratrechina longicornis (Lester & Tavite 2004), which is known for its ability to rapidly find food sources. The diet of A. gracilipes is varied, and it can be best described as “scavenging predator”. Prey selection includes small isopods, myriapods, molluscs, arachnids, and insects, to large land crabs, birds, mammals, and reptiles. Although foragers lack a sting, they may subdue and kill prey by spraying formic acid. Diet is supplemented by nectar from plant nectaries and honeydew excreted by homopterans, which are tended on stems and leaves of a wide variety of tree and shrub species (Harris and Berry, 2008).
Native range is unclear, although it is thought to have possibly come from West Africa. This species has spread to many other localites and is now found in Hawaii. This species has not yet been found in the continental United States, but it is one that is being closely monitored for. Currently, it is known to occur in American Samoa,
Christmas Island (Indian Ocean),
Cocos (Keeling) Islands,
French Polynesia (Polynésie Française),
Malaysia, Marshall Islands,
Micronesia, Federated States of (FSM),
New Caledonia (Nouvelle Calédonie),
Northern Mariana Islands,
Papua New Guinea,
Reunion (La Réunion),
United States (Hawaii),
and Wallis and Futuna (distribution from Global Invasive Species Database).
Harris, R. and J. Berry. 2008. Landcare Research, Manaai Whenua, Invasive Invertabrates: Anoplolepis gracilipes (Smith). Web article: http://www.landcareresearch.co.nz/research/biocons/invertebrates/Ants/invasive_ants/anogra_info.asp Accessed 7 November 2008.
Lester, P.J. and A. Tavite 2004: Long-legged ants (Anoplolepis gracilipes) have invaded the Tokelau Atolls, changing the composition and dynamics of ant and invertebrate communities. Pacific Science 58: 391–402.
Lowe, S. Browne, M., Boudjelas, S. and De Poorter, M. 2004. 100 of theWorld's Worst Invasive Alien species: A Selection from the Global Invasive Species Database, Gland,Switzerland: Invasive Species Specialist Group.
Global Invasive Species Database: Anoplolepis gracilipes-http://www.issg.org/database/species/ecology.asp?si=110&fr=1&sts=tss
Australian Government, Threatened species and ecological communities: Loss of biodiversity due to the yellow crazy ant on Christmas Island, Indian Ocean-http://www.environment.gov.au/biodiversity/threatened/ktp/christmas-island-crazy-ants.html
Introduced species summary Project: Yellow Crazy Ant (Anoplolepis gracilipes)-http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Anoplolepis_gracilipes.html