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Tawny Crazy Ants By Lawrence “Fudd� Graham, Ph.D., Coordinator of the Alabama Fire Ant Management Program, Auburn University
Al ab ama Tu rf Tim e s > >> Fall 201 6
T
awny crazy ants 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 (see Figure 1). These ants were found in Mobile County in the early summer of 2014 near Theodore, AL. If you try to find information on the web or in the literature, the results may be confusing. Before 2012, when its identity was confirmed, the tawny crazy ant was known by a variety of other common names (Caribbean crazy ant, hairy crazy ant and Rasberry crazy ant). 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
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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. Tawny crazy ants are often confused with the Argentine ant. The biology and general appearance of these two species are very similar. If you are not familiar with both species, it can be difficult to tell them apart. Both species form supercolonies with a large numbers of worker ants that take care of multiple queen nests. However, some traits can help the untrained eye tell the difference
between workers of the two species. Tawny crazy ant workers are small, orange to reddish-brown, hairy ants. If you look at them under magnification, they have fine hairs covering much of the body and a few larger, stiff erect hairs (Photo 1). The argentine ant workers are dark brown, and they lack the erect, visible hairs and have a black appearance (Photo 2). Trails of the tawny crazy ant are fast moving, erratic and wide. If an insecticide treatment has been applied for them, there may be large numbers of dead workers in corners and along walls. Trails of the Argentine ant are usually narrow (less than 1/2" wide), and the workers tend to stay on the trail. Argentine ants tend to follow structural guidelines such as sidewalk edges. There will not be piles of dead workers associated with Argentine ants. Both of these ants will tend honeydew-producing insects, so trails of both species can be seen on the bark of trees as they move up the tree to collect the sugary honeydew. Tawny crazy ant colonies can be found nesting in, on and under anything that can provide moisture. They have been found in mulch, leaf litter and landscape objects, under loose tree bark, pots and natural debris, and in signs and structures. One of the first measures of control is to clean up anything that the ants might be able to nest in or under. No one has ever witnessed a mating flight of tawny crazy ants. Tawny crazy ants spread by a process called budding. This occurs when a one or more queens from a colony moves or is relocated to an area outside of the parent colony. Ed Lebrun in Texas has found that the parent colony expands its range by only several hundred feet a year, so movement to new areas is usually facilitated by human movement in cars, trash, mulch, potted plants, etc. Many of the sites where tawny crazy ants first became established in the Southeast are near ports. In areas where tawny crazy ants are well established, workers can number in the millions. The colonies have multiple queens that share reproduction in the nest. This allows the colonies to reach very large populations of workers. These colonies can occupy wide swaths of land. The initial area in Theodore