Taxonomic name: Paratrechina longicornis (Latreille, 1802)
Synonyms: Formica gracilescens Nylander (1856) , Formica longicornis Latreille (1802) , Formica vagans Jerdon (1851) , Paratrechina currens Motschoulsky (1863) , Paratrechina longicornis (Latreille) (1925), Prenolepis (Nylanderia) longicornis Emery (1910) , Prenolepis longicornis Roger (1863) , Tapinoma gracilescens F. Smith (1858)
Common names: crazy ant, hairy ant, higenaga-ameiro-ari, long-horned ant, slender crazy ant
Organism type: insect
Paratrechina longicornis (the crazy ant) is a tramp ant, which, by definition, is an ant that is widely dispersed through commerce and other human-assisted avenues. It is extremely easy to identify by observing its rapid and erratic movements. Paratrechina longicornis is highly adaptable to various environments and can be a major pest. It occurs in large numbers in homes or outdoors and is capable of displacing other ants and possibly other invertebrates. Paratrechina longicornis forages over long distances away from its nest, making the nest hard to find and the ants difficult to control.
Crazy ant (Paratrechina longicornis) is extremely easy to identify by observing its rapid and erratic movements. The antennae have 12-segments without a club and the scape, the basal segment of the antenna, is extraordinarily long with the apex surpassing the posterior border of the head by at least one-half the scape length. Workers are relatively small (2.3-3mm). Head, thorax, petiole and gaster are dark brown to blackish and the body often has a faint bluish iridescence. All workers in a colony are monomorphic and have only one node between the propodeum and the gaster. Eyes are elliptical, strongly convex, and placed close to the posterior border of the head. Legs are extraordinarily long. The head is elongate and the mandibles narrow. Each mandible has five teeth. A stinger is lacking but P. longicornis may bite an intruder and curve its abdomen forward to inject a formic acid secretion from its acidopore onto the wound. Confirmation of identification may be made with the aid of a hand lens, through which the extremely long antennal scape, long legs and erect setae are very apparent. (Creighton, 1950; Harris and Berry, 2005; Nickerson and Barbara, 2000; and Onoyama and Morisita, 2003).
Please click on AntWeb: Paratrechina longicornis for more images and assistance with identification. The AntWeb image comparison tool lets you compare images of ants at the subfamily, genus, species or specimen level. You may also specify which types of images you would like to comare: head, profile, dorsal, or label.
Please see PaDIL (Pests and Diseases Image Library) Species Content Page Ants: Crazy ant for high quality diagnostic and overview images.
Please follow this link for a fully illustrated Lucid key to common invasive ants [Hymenoptera: Formicidae] of the Pacific Island region [requires the most recent version of Java installed]. The factsheet on Paratrechina longicornis contains an overview, diagnostic features, comparision charts, images, nomenclature and links. (Sarnat, 2008)
agricultural areas, ruderal/disturbed, urban areas
Crazy ant (Paratrechina longicornis) is highly adaptable, living in both very dry and rather moist habitats. It often nests some distance away from its foraging area and is usually associated with disturbance. They are a common pest ant in houses and seem peculiarly adapted to the interior and immediate vicinity of human habitations. It nests in such places as trash, refuse, cavities in plants and trees, rotten wood, in soil under objects and also have been found under debris left standing in buildings for long periods of time. A crazy ant nest site can be found by looking for workers carrying food back to the nest. P. longicornis can also be found in other environments such as beaches, dry tortugas, geothermal areas, farms and even ships. It is also present in some native vegetation in the tropics, such as in conservation areas on offshore islands. In cold climates, the ants nest in centrally heated buildings. On beaches at high tide, nests can be found submerged underwater and are probably protected from flooding by air trapped in the nest galleries (Harris and Berry, 2005; Longino, 2004; and Nickerson and Barbara, 2000).
Crazy ant (Paratrechina longicornis) is an extremely hardy species. Its ability to invade a varying degree of habitats makes it serious threat. It occurs in large numbers in homes or outdoors. They forage long distances away from the nest, making them hard to find and subsequently make it difficult to control. P. longicornis is a common tramp that invades houses and heated buildings. It is known to transport pathogenic microbes in hospitals. P. longicornis is capable of displacing other ants and possibly other invertebrates. It is also difficult to control with current commercially available chemical controls because they show limited effectiveness. Nests can be in cracks in concrete or around wharf piles, which makes nests often difficult to locate and control. (Harris and Berry, 2005; and Nickerson and Barbara, 2000).
Paratrechina longicornis is involved in an important mutualistic relationship with the eggs of the lizard Mabuya longicaudata in its native range of Taiwan. In high moisture enviroments reptile eggs are able to condense water on their surfaces. These small water droplets are collected by P. longicornis. When water droplets and P. longicornis were experimentally removed from the eggs of M. longicaudata the eggs were attacked by the egg predator ant Pheidole taivanensis. Both ant species actively searched for the reptilian eggs, with P. taivanensis usually finding eggs first. In the absence of P. longicornis, P. taivanensis predation dramatically reduced lizard egg survival. However when P. longicornis found nests later they were usually able to displace the egg predator ant (Huang, 2008).
The common name "crazy ant" arises from the ants characteristic erratic and rapid movement, not following trails as often as other ants. P. longicornis is morphologically distinctive and is one of the few Paratrechina species that is not consistently mis-identified in collections (Harris and Berry, 2005; and Nickerson and Barbara, 2000).
Native range: Africa and Asia (Nickerson and Barbara, 2000).
Known introduced range: Australasia-Pacific Region, Europe, North America, and South America (Andersen et al. 2004; Freitag et al. 2000; Nickerson and Barbara, 2000; and Torres and Snelling, 1997).
Introduction pathways to new locations
Nursery trade: On 26 October 1990, Greg Mayer, Tina Kuklenski, and Scott Miller sampled invertebrates from a large shipment (an entire barge) of potted plants being unloaded at Guana Island, British Virgin Islands (BVI). The shipment was infested with large numbers of insects and snails, and included P. longicornis (Miller, 1994).
Other: Human-mediated dispersal has helped the spread of P. longicornis at local, regional, national and international scales (Harris et al. 2005). It can be associated with any commodity and transport mode from countries with established populations and is commonly intercepted on air and sea cargo, including fresh produce, timber, empty sea containers and personal baggage (Simon O'Connor pers comm).
Ship: On 26 October 1990, Greg Mayer, Tina Kuklenski, and Scott Miller sampled invertebrates from a large shipment (an entire barge) of potted plants being unloaded at Guana Island, British Virgin Islands (BVI). The shipment was infested with large numbers of insects and snails and included P. longicornis (Miller, 1994).
Local dispersal methods
Natural dispersal (local): Natural dispersal is primarily by budding. Neither queens nor males appear to fly (Trager 1984). It is a rapid coloniser and often the first species to arrive in a newly disturbed area (Lee 2002) (Harris and Berry, 2005).
Preventative measures: Early detection by active surveillance and subsequent nest treatment is the best way to prevent any ant species from establishing in novel environments. Pitfalls and attractant baits are both methods that can yield good results (Simon O'Connor pers.comm).
The Pacific Ant Prevention Programme is a proposal prepared for the Pacific Plant Protection Organisation and Regional Technical Meeting for Plant Protection. This plan aims to prevent the red imported fire ant and other invasive ant species with economic, environmental or social impacts from establishing within or spreading between countries in the Pacific.
A detailed pest risk assessment for the eight species ranked as having the highest potential risk to New Zealand (Anoplolepis gracilipes, Lasius neglectus, Monomorium destructor, Paratrechina longicornis, Solenopsis geminata, Solenopsis richteri, Tapinoma melanocephalum, Wasmannia auropunctata) was prepared as part of 'The invasive ant risk assessment project', Harris et al. 2005., for Biosecurity New Zealand by Landcare Research. The invasive ant risk assessment for Paratrechina longicornis can be viewed at Paratrechina longicornis risk assessment
Please see Paratrechina longicornis information sheet for more information on biology, distribution, pest status and control technologies.
Cultural: Non-chemical control is based on exclusion through good housekeeping practices and cleanliness, eliminating food sources. Crazy ants often nest outdoors so prevention of their entrance by caulking exterior penetrations and weather-stripping may aid in their control (Nickerson and Barbara, 2000).
Chemical: Inside buildings, chemical controls are based on baits, dusts and spot treatments with residual sprays. Outdoor treatments include chemical formulations such as baits, granules, dusts, and sprays (Nickerson and Barbara, 2000).
Please follow this link for more detailed information on the management of Paratrechina longicornis compiled by the ISSG.
Crazy ant (Paratrechina longicornis) foragers are opportunistic omnivores, feeding on live and dead insects, seeds, honeydew, fruits, plant exudates and many household foods. P. longicornis thrive in places such as shops and cafes, where workers may be seen transporting crumbs and insects. They apparently have a seasonal preference for a high-protein diet and during the summer months may refuse honey or sugar baits. They are attracted to honeydew producing homopterans in spring and autumn/fall. Honeydew is obtained by tending plant lice, mealy bugs and scales. Foragers will also collect seeds. Large prey items, such as a lizard, are carried by a highly concerted group action. Workers feed on many household foods, such as meat, grease, sweets, fruits, vegetables and liquids (Smith 1965)" (Harris and Berry, 2005; and Nickerson and Barbara, 2000).
Crazy ant (Paratrechina longicornis) colonies are polygyne. Nests contain up to 2000 workers and 40 queens. Reproduction is throughout the year in warm climates but more restricted in cooler climates. Workers are probably sterile. Colonies occur in temporary nests, are highly mobile, and will move if disturbed. These ants can nest in a variety of locations from dry to moist environments (Harris and Berry, 2005).
Crazy ant (Paratrechina longicornis) colonies range from moderate to heavily populous. The colonies may raise sexuals at any time of the year in warmer regions, but in the seasonal climate of north Florida, alate production is apparently limited to the warm rainy months of spring through late summer. On warm, humid evenings, large numbers of males gather outside nest entrances and may mill about excitedly. Workers patrol vegetation and other structures nearby. Periodically, a dealate queen emerges. Trager (1984) has suggested that mating occurs in such groupings around the nest entrance. Wings of queens are removed while still callow and males were never observed to fly or use their wings in any way. However, in several cases it has been observed that males frequently appear at lights (Nickerson and Barbara, 2000).
Reviewed by: Simon O'Connor Coordinator, Pacific Ant Prevention Programme Secretariat of the Pacific Community New Zealand
Principal sources: Harris, R.; Abbott, K.; Barton, K.; Berry, J.; Don, W.; Gunawardana, D.; Lester, P.; Rees, J.; Stanley, M.; Sutherland, A.; Toft, R. 2005: Invasive ant pest risk assessment project for Biosecurity New Zealand.
Nickerson and Barbara, 2000 Paratrechina longicornis
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
Last Modified: Monday, 4 October 2010