Most recently reviewed by: Pat Porter (2018)
Common Name(s): Rasberry Crazy Ant, Tawny Crazy Ant
Tawny crazy ants are fast becoming an economic, ecological and nuisance pest in the southern United States. This ant, also known as the Caribbean crazy ant, hairy crazy ant and Rasberry crazy ant, has been a serious problem in parts of Florida and Texas for over ten years. It is spreading across the southeastern United States, most often through human assistance. Huge numbers of this new ant can literally cover the landscape in industrial parks and residences. In 2012 the ant was officially identified as Nylanderia fulva (Mayr) by Gotzek et al., and given the approved common name the tawny crazy ant (fulva is the Latin word for tawny). While our understanding of the biology and management of the tawny crazy ant is increasing, much remains to be learned.
Suspect tawny crazy ant if you see a lot of ants with the following general characteristics:
- Appearance of extraordinarily dense populations of uniformly-sized 1/8 inch long, reddish-brown ants in the landscape; foraging occurs indoors from outside.
- Ants that form loose foraging trails as well as foraging that occurs randomly (non-trailing); ants crawl rapidly and erratically (hence the description “crazy” ant).
- Ant colonies (workers, queens, and brood including whitish larvae and pupae) occur under landscape objects like rocks, timbers, piles of debris, etc. These ants do not build centralized nests, beds, or mounds.
Origin and Distribution
The tawny crazy ant has the potential to spread well beyond its current range in the southern United States. However, it is a semi-tropical ant and potential northern distribution could be limited by cooler weather conditions. It has been reported in Alabama, Florida, Georgia, Louisiana, Mississippi and Texas.
The EDDMapS mapping system for tawny crazy ant is available if you would like determine if the ants are present in your county. EDDMapS web page:
Habitat & Hosts
Tawny crazy ants can reach extraordinary population densities. They are social insects that live in large colonies or groups of colonies that seem to be indistinguishable from one another. Colonies contain many queen ants, worker ants, and brood consisting of larval and pupal stages. Pupae are “naked” or without cocoons. They periodically produce winged male and female forms called swarmers, alates, or reproductives. The size of infestations can be large and display super colony (unicolonial) behavior.
Tawny crazy ant foraging trails are quite apparent (≥10 cm wide) and individuals forage erratically. They prefer shaded areas and avoid unshaded areas. Foraging trails will often be found going up and down trees, fences, following seams in concrete surfaces, following structural barriers and in large open shady grassy areas.
Tawny crazy ant colonies can be found under or within almost any object or void, including stumps, soil, concrete, rocks, potted plants, etc. that retain moisture. Nests primarily occur outdoors, but worker ants will forage indoors, into homes and other structures.
Tawny crazy ants eat almost any organic material; they are omnivorous. Worker ants commonly “tend” sucking hemipterous insects such as aphids, scale insects, whiteflies, mealy bugs, and others that excrete a sugary (carbohydrate) liquid called “honeydew” when stimulated by the ants. Workers are attracted to sweet parts of plants including nectaries or damaged and over-ripe fruit. Worker ants also consume other insects and small vertebrates for protein.
Despite the observation of winged male and female reproductive tawny crazy ants, mating (nuptial) flights have not been observed in the field. This contributes to the assumption of many entomologists that tawny crazy ant colonies propagate by a process known as “budding.” In such a system, mating and breeding would likely occur in the vicinity of the population boundaries, which would result the creation new colonies on the periphery of the established population. The pace of tawny crazy ant colony expansion has been observed to be ~65 and ~95 ft. per month in neighborhoods and industrial areas respectively and ~650 ft. /year in rural landscapes.
Egg, larva, pupa and adult
ManagementIf you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.
Management: What can you do for them?
Many of the typical standalone methods of effectively managing other ants do not provide adequate control of the tawny crazy ant. Because colonies predominantly nest outdoors, reliance on indoor treatments is an ineffective approach to controlling these ants when foraging inside structures. Effective tawny crazy ant management requires a multi-tiered Integrated Pest Management approach that involves landscape modification, elimination of food sources, landscape treatment, and lastly, if necessary, barrier treatment for structures. In some states there exists a FIFRA Section 18 Quarantine Exemption Use label that allows perimeter application of Termidor® (BASF) 3-feet up and 10-feet out from the infested structure for management of tawny crazy ants. Additionally, several insecticidal products are labelled to allow application wherever tawny crazy ants are observed to be active on a property.
It should be noted that chemical applications alone are not the answer. They are part of the solution, and chemical applications by themselves will only give minimal reduction in the tawny crazy ant population. Good integrated pest management principles should be followed to obtain population reduction through habitat modification which will allow the chemical treatments to perform better. Check with your local Cooperative Extension Specialist to obtain recommendations for chemical management strategies targeting the tawny crazy ant in your county.
Landscape Modification: Cultural control practices including the removal of harborage such as fallen limbs, rocks, leaf litter, potted plants, and just about anything contacting the ground that isn’t absolutely necessary should be attempted. Cultural control methods can also include altering the moisture conditions in a landscape. Tawny crazy ants prefer damp conditions, so reducing the amount of irrigation, repairing leaks, leveling low areas and improving drainage should help. You may need to alter your landscape, i.e., remove mulch, severely prune landscape plants where the ants prefer to forage and nest, and tend honeydew producing insects.
Elimination of Food Sources and Landscape Treatment: Populations of honeydew producing insects (i.e. aphids and scale insects) should be managed to reduce the availability of this food resource. Often, products containing the active ingredient imidacloprid or other systemic neonicotinoids are a good option for managing these insects. Additionally, consider eliminating or relocating compost, pet food, etc. Periodic (follow intervals specified on the pesticide label) lawn treatment with a pyrethroid insecticide such as lamda-cyhalothrin will help to reduce foraging ants. A single application of a fipronil granular product may also be considered. We also suggest spraying 4-5 foot up each of the large trees on your property to help keep the ants from foraging into trees. Broadcast applications of the products should be made to the yard and other areas of the landscape. Be sure to check regulations in your area for restrictions to applications of a pyrethroid to landscaped areas. It is important that all areas be treated with an appropriately labeled product. Spot treatments are not successful.