Sign up for the iWire to get breaking news, event info and the species spotlight.

Go Back | Printer Friendly Fact Sheet

Nylanderia fulva (formerly Nylanderia sp. near pubens)

Tawny Crazy Ant (formerly Rasberry Crazy Ant)

Synonym(s): formerly Nylanderia sp. near pubens
Class: Insecta
Order: Hymenoptera
Family: Formicidae

Photographer: Bastiaan Drees
Source: Texas A&M University


Adult Description: The Rasberry 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. The Rasberry crazy ant is a social insect that is usually found in extremely large numbers and lives in large colonies or groups of colonies that seem to be indistinguishable from one another.

Aside from the worker ants, the reproductive males and females of the Rasberry crazy ant 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.

Larva Description: Pupae are "naked" or without cocoons. They periodically produce winged males and female forms called sexuals or reproductives. 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

Ecological Threat: While the exact impact of the Rasberry crazy ant on the local ecology is unknown, a related species in this genus, Nylanderia fulva, has been a serious pest in rural and urban areas of Colombia and South America. In this case, they reportedly displaced all other ant species and caused small livestock (e.g. chickens) to die of asphyxia. Larger animals, such as cattle, have been attacked around the eyes, nasal fossae and hooves. The ants also cause grasslands to dry out (dessicate) because the ants aggravate sucking insect pests (hemipterans) since the ants feed on the sugary "honeydew" produced by these plant feeding insects. Further, wildlife, such as nesting songbirds, are irritated by Rasberry crazy ants. Masses of crazy ants covering the ground and trees likely affect ground and tree-nesting birds and other small animals and cause wildlife to move out of the area. These ants are even displacing red imported fire ants in areas of heavy infestation. Ironically, after experiencing the Rasberry crazy ant, most residents prefer the fire ant!

In addition to ecological damage, this ant also causes threat of destruction to many human facilities :

-Electrical equipment: In areas infested by the Rasberry crazy ant, large numbers of ants have accumulated in electrical equipment, causing short circuits and clogging switching mechanisms and equipment failure.

-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: Rasberry crazy 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.

Biology: No mating (nuptial) flights have been observed in the field, despite the periodic development of winged male and female ants, called sexuals or reproductives. 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. Annual rate of spread by ground migration is not known. However, while their actual mechanism for distribution is unknown, the Rasberry crazy ant is an incredibly aggressive and destructive pest species. They are known to rapidly colonize and take over various habitats, including human-built establishments. Homeowners fear infestations because iradication is nearly impossible once a colony has been formed.

History: The Rasberry crazy ant was first discovered near Houston, Texas in 2002 by Tom Rasberry, a pest control man who has the ant named in his honor. The ant quickly turned into a problem for local residents and businesses infiltrating homes and destroying electrical work. 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 where the ants are indigenous. Their exact means of entry are unknown, but precautions are being taken to avoid the spread of Rasberry crazy ants.

U.S. Habitat: Rasberry 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.


Native Origin: Believed to be from South America

U.S. Present: The Rasberry crazy ant has only been found in the state of Texas.

Distribution in Texas: The Rasberry crazy ant has only been found in the state of Texas (near Pasadena) since 2002. High densities of these ants have been documented in localized spot infestations in southeast Houston (Harris County), including Houston, Pasadena, Deer Park, Friendswood, San Jacinto Port, Pearland, Seabrook and La Porte.

Additional localized infestations have also been confirmed from areas in Bexar, Brazoria, Cameron, Fort Bend, Chambers, Galveston, Hardin, Harris, Hidalgo, Jefferson, Jim Hogg, Liberty, Montgomery, Nueces, Orange, Walker, and Wharton counties. New infestations are suspected beyond these areas. However, sample identifications have not been confirmed. This ant has the potential to spread well beyond the current range in coastal Texas. This is a semi-tropical ant and potential northern distribution will be limited by cooler weather conditions.

If you believe you have found a tawny crazy ant, please report this species.


Nylanderia pubens, the hairy crazy ant found in Neotropical regions and Florida. These two ant species are visually identical and they are believed to be very closely related. However there is still uncertainty as to how closely related they are.


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.


Google Search: Nylanderia fulva (formerly Nylanderia sp. near pubens)
Google Images: Nylanderia fulva (formerly Nylanderia sp. near pubens)
NatureServe Explorer: Nylanderia fulva (formerly Nylanderia sp. near pubens)
Bugwood Network Images: Nylanderia fulva (formerly Nylanderia sp. near pubens)

Text References

Drees, Bastiaan M. (2009). Rasberry Crazy Ant.

Horn, Katherine. (2010). Examining Competitive Interaction Between Rasberry Crazy Ants (Paratechina pubens) and Red Imported Fire Ants (Solenopsis invicta) Using Laboratory and Field Studies. Rice University.

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: (Main Resource: see link below)

Dr. Jerry Cook - Sam Houston State University -

Data Source

Texas A&M University Urban and Structural Entomology

Last Updated: 2011-09-21 by Amber Bartelt - Sam Houston State University