The tawny crazy ant, Nylanderia fulva (Mayr), is a new exotic invasive ant species from South America with widespread distribution from Texas to South Carolina. They are fast becoming an economic, ecological and nuisance pest in the southeastern United States. They have been a serious problem in parts of Florida and Texas for more than ten years and have begun spreading to other states. Like many other pest ant species, tawny crazy ants are from South America. The earliest report of the tawny crazy ant in the U.S. is from Texas in 1938, but the ant did not become established at that time. Tawny crazy ants that were found in Texas around 2000 likely represent a recent, separate introduction, according to work by Jason Meyers at Texas A&M. Due to confusion of its identity with another related species of ant, it is unknown exactly when tawny crazy ants arrived in Florida, but they have been there as least as long or longer than they have been in Texas. Between 2009 and 2014, they were reported in Louisiana, Mississippi, Alabama and Georgia.
The tawny crazy ant’s biology and general, visual appearance, to the untrained eye, is similar to that of another South American invasive ant species common in the South, the Argentine ant (Linepithema humile) (known to most as “sugar ants”). While the tawny crazy ant first became a problem in the 1990’s, the Argentine ant has been established in the south for more than 100 years. Neither are native to the US.
The tawny crazy ant was formerly known as the Rasberry crazy ant (after a pest control operator, Mr. Tom Rasberry, the discoverer of N. fulva in Texas), the hairy crazy ant (under a microscope the ant appears hairy) and the Caribbean crazy ant (given its FL distribution). In 2012 the ant was officially identified as Nylanderia fulva (Mayr) by Gotzek et al., and later was given the official approved common name of the tawny crazy ant (fulva is the Latin word for tawny).
These ants are known for the appearance of extraordinarily dense populations of uniformly-sized 1/8-inch-long, reddish-brown ants in the landscape. Foraging occurs indoors from outside. They move in a quick, erratic, "crazy" manner. Homeowners have reported that "the ground is moving" in areas of heavy infestation. Tawny crazy ants do not form mounds in the landscape, although they can tunnel in sandy soil, contrary to previous reports.
In infested areas, large numbers of tawny crazy ants have caused great annoyance to residents and businesses. In some situations, it has become difficult for residents to enjoy time in their yards. Companion animals may, in some cases, attempt to avoid the outdoors as well, and wildlife, such as nesting songbirds, can be affected. The cumulative economic impact of this invasive ant species is currently unknown.
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