Bastiaan Drees,
Texas A&M University
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Synonym(s): formerly Nylanderia sp. near pubens; Rasberry crazy ant
Adult Description: The tawny crazy ant, called "crazy" for how they rapidly and randomly move about, are medium-small, 2.6-3 mm long, monomorphic, golden-brown to reddish-brown ants that have a smooth and glossy body surface, covered with dense hairs. Worker ants have long legs and antennae and their bodies have numerous, long, coarse hairs. Their heads are shiny, sparsely pubescent, and subcordate. The antenna have 12-segments with no club, and their antennal scape is nearly twice the width of the head. After feeding, the ant's gaster (portion of the rear abdomen) will appear to be striped due to stretching of the light-colored membrane connecting the segments of the gaster. Its thorax is densely pubescent with long, abundant light-brown hairs. There is a small circle of hairs, called the acidopore, present at the tip of the abdomen, as opposed to the typical stinger found in most ants, a characteristic of formicine ants.
Reproductive males and females: are similar in color but are larger and possess wings. Queens are larger still, and are responsible for producing the millions of larvae within the colony.
If you believe you have found a tawny crazy ant, please report this species.
Larva Description: Pupae are "naked" or without cocoons and periodically produce winged males and female forms (sexuals). There can be millions of pupae within any one colony of Rasberry crazy ants. Sometimes colonies are so large that the individuals are indistinguishable from those of neighboring colonies and a "super colony" may result with tremendous numbers.
Host Plant: None
History: A mistaken identity with Nylandaria pubens left the Tawny Crazy Ant unconfirmed in Florida, potentially as early as 1990. The first confirmed reports for this invasive species was near Houston, Texas in 2002 by Tom Rasberry (hence the alternative common name Rasberry crazy ant), a pest management professional. The ant quickly turned into a problem for local residents and businesses infiltrating homes and destroying electrical work. Initially, high densities of these ants were reported southeast Houston (Harris County), including Houston, Pasadena, Deer Park, Friendswood, San Jacinto Port, Pearland, Seabrook and La Porte. Even NASA called on Rasberry and others in order to eradicate the ant from electrical wiring at NASA facilities. The ant is believed to have traveled to the U.S. aboard a commercial ship, probably from South America. Their exact means of entry are unknown, but precautions are being taken to avoid the spread of the tawny crazy ants.
Upon confirmation in Texas (2002), it was confirmed in Florida (2007), and subsequently , Louisiana (2011, Mississippi (2014), Alabama (2014, and Georgia (2017).
Biology: Being a social insect, the tawny crazy ant, is usually found in extremely large numbers and lives in large colonies or groups of colonies that seem to be indistinguishable from one another. However, it is an incredibly aggressive and destructive pest species. They are known to rapidly colonize and take over various habitats, including human-built establishments.
Despite the periodic development of winged male and female ants, called sexuals or reproductives, they do not have mating (nuptial) flights. This indicates that colonies spread or propagate by "budding" with breeding occurring at/near the edge of the nest, creating new colonies at the periphery.
Ecological Threat: The tawny crazy ant is displacing both native and non-native ant species, and negative impacts on other vertebrates and invertebrates are likely; these ants are even displacing red imported fire ants in areas of heavy infestation.
Nylanderia fulva has been a serious pest in rural and urban areas. In Columbia, where they are also invasive, displaced all other ant species, smother small livestock (e.g. chickens) to asphyxia, and attack larger livestock (cattle) around the eyes, nasal fossae and hooves. The ants feed on the sugary "honeydew" produced by these plant feeding insects and, in exchange, provide protection from other predators. Masses of crazy ants covering the ground and trees likely affect ground and tree-nesting birds and other small animals and may cause wildlife to move out of the area.
In addition to ecological damage, this ant also causes threat of destruction to many human facilities:
Electrical and residential : In areas infested by the Tawny crazy ant, large numbers of ants have accumulated in electrical equipment, causing short circuits and clogging switching mechanisms and equipment failure. Homeowners fear infestations because eradication is nearly impossible once a colony has been formed. Ironically, after experiencing the tawny crazy ant, most residents prefer the fire ant!
Agriculture: These ants show the likelihood of being transported through movement of almost any infested container or material. Thus, movement of garbage, yard debris, bags, loads of compost, potted plants, bales of hay, can transport these ant colonies by truck, railroad, and airplane.
Humans: These ants do not have stingers. In place of a stinger, worker ants possess an acidopore out the end of the abdomen, which can excrete chemicals for defense or attack. They are capable of biting, and when bitten, they cause a relatively sharp pain that quickly fades.
US Habitat: Tawny crazy ants eat almost anything; they are omnivorous. Worker ants commonly "tend" sucking hemipterous insects such as aphids, scale insects, whiteflies, mealybugs, and others that excrete a sugary (carbohydrate) liquid called "honeydew" extracted from host plants when stimulated by the ants. Workers are also attracted to sweet parts of plants including nectaries, damaged, and over-ripe fruit.
Distribution
Native Origin: Brazil, Paraguay and Uruguay
Same Native Range as the invasive Red Imported Fire Ant and Argentine AntsUS States: AL, FL, GA, LA, MS and TX.
Texas: Confirmed in Angelina, Bexar, Brazoria, Brazos, Cameron, Chambers, Colorado, Comal, Fayette, Fort Bend, Galveston, Hardin, Harris, Hays, Hidalgo, Jasper, Jefferson, Jim Hogg, Liberty, Matagorda, Montgomery, Nueces, Polk, Orange, San Augustine, Travis, Victoria, Walker, Wharton and Williamson counties. New infestations are suspected beyond these areas.
If you believe you have found a tawny crazy ant, please report this species.
Resembles: Nylanderia pubens, the hairy crazy ant found in Neotropical regions and Florida; and the main species behind the delayed confirmation in Florida.
These two ant species are visually identical and they are believed to be very closely related.
Management: Many of the typical control tactics for other ants do not provide adequate control of the Rasberry crazy ant. Because colonies predominantly nest outdoors, reliance on indoor treatments to control these ants foraging inside structures are not effective. Rasberry crazy ant workers are not attracted to most bait products and the one known product they are attracted to (Whitmire Advance Carpenter Ant Bait formulation containing abamectin), does not offer enough control. Effective products involved with the treatments are not readily available to the consumer. If you suspect your house or property is infested with these ants, call a professional pest control provider. After treatment, or when making multiple applications over time, piles of dead ants must be swept or moved out of the area in order to treat the surface(s) beneath.
Text References
Drees, Bastiaan M. (2009). Rasberry Crazy Ant. http://hdl.handle.net/1969.1/87618
Horn, Katherine. (2010). Examining Competitive Interaction Between Rasberry Crazy Ants (Paratechina sp.nr. pubens) and Red Imported Fire Ants (Solenopsis invicta) Using Laboratory and Field Studies. Rice University. http://gradworks.umi.com/14/86
MacGown. J., B. Layton. (2009). The Invasive Rasberry Crazy Ant, Nylanderia sp. Near pubens (Hymenoptera: Formicidae), Reported from Mississippi. Midsouth Entomologist. 3 : 44-47.
Internet Sources:
http://midsouthentomologist.org.msstate.edu
http://bugguide.net
http://www.issg.org
http://urbanentomology.tamu.edu/urban-pests/ants/rasberry/ (Main Resource: see link below)
http://beta-www.tpwd.state.tx.us
Experts:
Dr. Jerry Cook - Sam Houston State University - jcook@shsu.edu
Data Source
Last Updated: 2025-10-23 by Ashley Morgan-Olvera, TISI