common name: Caribbean crazy ant (proposed common name)
scientific name: Nylanderia (=Paratrechina) pubens (Forel) (Insecta: Hymenoptera: Formicidae: Formicinae)
Introduction - Synonymy - Distribution - Description - Life Cycle - Foraging and Feeding - Nest Sites - Pest Status - Management - Selected References
Beginning about 2000, reports have escalated of a golden-brown to reddish-brown "crazy ant" infesting properties in and around West Palm Beach, Florida. Thick foraging trails with thousands of ants occur along sidewalks, around buildings, and on trees and shrubs. Pest control operators using liquid and/or granular broad-range insecticides appear unable to control this nuisance ant.
Figure 1. A Caribbean crazy ant, Nylanderia pubens (Forel), worker. Photograph by F.J. Santana, Sarasota County.
Paratrechina pubens Forel 1893
Nylanderia pubens (Forel) was originally described as Paratrechina pubens Forel from St. Vincent, Lesser Antilles, and has been found on other West Indian islands, including Anguilla, Guadeloupe, and Puerto Rico (Trager 1984). The species was renamed Nylanderia pubens in 2010 (LaPolla et al.).
Samples of Nylanderia pubens collected in Coral Gables and Miami, Florida, date from 1953 (Trager 1984). Klotz et al. (1995) report infestations in Boca Raton, Homestead, and Miami and state that "in 1990, hundreds of these ants were found on the second floor of a large Miami hospital." Deyrup et al. (2000) report that it "is abundant on the campus of the University of Miami, where it resembles a pale Nylanderia bourbonica, foraging on sidewalks and running up and down tree trunks." L. Davis, Jr. (2003 personal communication) has seen these ants from Everglades National Park, Fort Lauderdale, Jacksonville, and Port St. Lucie. Specimens from Sarasota (F. Santana 2003, personal communication) were also confirmed. These ants seem to have large populations where they occur and are considered a pest in Colombia (Davis 2003, personal communication).
In the West Palm Beach area, two heavily infested sites were observed about 3 miles west of the Intracoastal Waterway. These sites are adjacent to a utility right-of-way running to the port of Palm Beach (site of a Florida Power and Light electrical generating plant). The port may have been the point of debarkation of Nylanderia pubens into Palm Beach County.
Figure 2. A Caribbean crazy ant, Nylanderia pubens (Forel), distribution in Florida as of 2004. Drawing by L J. Warner, University of Florida.
In 2002, a significant infestation of an ant was found around Houston (Harris County), Texas, that is being referred to by the media and others as the "Rasberry crazy ant" (Nylanderia nr. pubens) because it was discovered by a pest control operator named Tom Rasberry. In his 2008 dissertation, Dr. Jason M. Meyers (Texas A&M) performed morphometric and phylogenetic identifications on the Texas ant and found that "Despite a previous, inadequate species description for the original concept of Nylanderia pubens (Forel 1893), morphological evidence alone does not suggest that a new species classification is warranted for the Texas populations" (Meyers 2008). It is therefore likely that the "Rasberry crazy ant" is the same as the "Caribbean crazy ant" being only an "intraspecific variation of Nylanderia pubens, frequently observed in insect species."
Nylanderia pubens is part of a group of ants referred to as "crazy ants" due to their quick and erratic movements. The Caribbean crazy ant is a medium-small (2.6 to 3 mm long), monomorphic, golden-brown to reddish-brown ant. The body surface is smooth and glossy, and covered with dense pubescence (hairs). After feeding, the ant's gaster (rear portion of the abdomen) will appear to be striped due to stretching of the light-colored membrane connecting segments of the gaster. Antennae have 12 segments with no club. The antennal scape is nearly twice the width of the head. This ant has one petiolar segment and does not sting.
Similar ants: Nylanderia guatemalensis (Forel 1885), the Guatemalan crazy ant, has pale middle and hind coxae, shorter, stouter, and darker pilosity (Davis 2003, personal communication), and is notably smaller than Nylanderia pubens, total length 2.0 to 2.5 mm as compared to 2.6 to 3.0 mm for Nylanderia pubens (Trager 2004 personal communication). Deyrup et al. (2000) state that Nylanderia guatemalensis is a common species in Dade, Broward and Monroe Counties, but is less common farther north to Hillsborough and Indian River counties, and Deyrup (2002) adds that it is found in south Florida, north to Sarasota and Indian River counties.
Prenolepis imparis (Say 1836), the false or small honey ant, has a severely constricted "hour-glass- shaped" alitrunk (mesosoma), and is found in north Florida, south into Orange County (Deyrup 2002).
Figure 3. The false or small honey ant, Prenolepis imparis (Say). Arrow shows constriction forming an "hour-glass" shaped alitrunk. Photograph by Tim Linksvayer, Carleton College.
Little is known of the Nylanderia pubens life cycle. During a cold winter morning in West Palm Beach, Florida, one dealate queen and several winged males were observed in a soil nest under a log, but the entire colony was not examined. In Paratrechina longicornis (Latreille), a related species, a single colony may have eight to 40 queens. It is assumed from observations at West Palm Beach that colonies have several hundred thousand individuals and appear to be polydomous (nesting in several locations) and polygamous (multiple queens).
Figure 4. Caribbean crazy ant, Nylanderia pubens (Forel), workers tending brood. Photograph by F.J. Santana, Sarasota County.
Figure 5. Caribbean crazy ant, Nylanderia pubens (Forel), queen (arrow) and workers, tending larvae. Photograph by F.J. Santana, Sarasota County.
Figure 6. Lateral view of a Caribbean crazy ant, Nylanderia pubens (Forel), worker. Photograph by John Warner, University of Florida.
Figure 7. Frontal view of the head of a Caribbean crazy ant, Nylanderia pubens (Forel), worker. Photograph by John Warner, University of Florida.
Figure 8. Acidopore (arrow) at apex of gaster of a Caribbean crazy ant, Nylanderia pubens (Forel), worker. Photograph by John Warner, University of Florida.
Figure 9. Lateral view of a Caribbean crazy ant, Nylanderia pubens (Forel), male reproductive. Photograph by John Warner, University of Florida.
Trails were not observed on a cold morning (approximately 48°F), but as the temperature increased (60°F), ants foraged from nest sites. Although thick trails were seen along sidewalks, trees, shrubs, and structures, no feeding activity was observed. It is assumed that as other Nylanderia species, N. pubens will scavenge for food, feed on dead insects, and tend honeydew producers. Sweet liquid ant bait was fed upon when placed directly on an active trail, but recruitment to the bait was not observed.
Figure 10. Caribbean crazy ants, Nylanderia pubens (Forel), feeding on NecDew© sweet ant bait. Photograph by Rudolph H. Scheffrahn.
Ants were observed emerging from soffits, between railroad ties used in landscaping, under wooden debris, underground electrical conduits, and cracks in cement. They will probably nest in numerous locations.
Figure 11. Nest of Caribbean crazy ant, Nylanderia pubens (Forel). Photograph by F.J. Santana, Sarasota County.
Most of the reports of Nylanderia pubens infestations have come from pest control operators in and around the southeast Florida "Treasure Coast" from West Palm Beach north to Port St. Lucie, where trails consisting of thousands of ants have been observed along sidewalks, buildings, and gardens, causing property owners to complain. Sprays and granular applications of residual insecticides seemingly have had little or no effect in controlling this non-biting nuisance ant.
Until research is done on management techniques, we recommend the use of contact residual insecticides sprayed along active trails and nest sites to reduce ant populations, followed a few days later by sweet ant baits placed at numerous locations along trails and frequently replaced with fresh bait. Always follow label directions.
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- Fasulo TR, Kern WH, Koehler PG, Short DE. 2005. Pests In and Around the Home. UF/IFAS. SW-126. (22 November 2005).
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- Forel A. 1893. Formicides de l'Antille St. Vincent, récoltées par Mons. H. H. Smith. Transactions of the Entomological Society of London 1893: 333-418.
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- LaPolla JS, Brady SG, Shattuck SO. 2010. Phylogeny and taxonomy of the Prenolepis genus-group of ants (Hymenoptera: Formicidae). Systematic Entomology 35: 118-131.
- Meyers JM. 2008. Identification, distribution and control of an invasive pest ant, Paratrechina sp. (HYMENOPTERA: FORMICIDAE), in Texas. Doctoral dissertation, Texas A&M University.
- Say T. 1836. Descriptions of new species of North American Hymenoptera, and observations on some already described. Boston Journal of Natural History 1: 209-305.
- Trager JC. 1984. A revision of the genus Paratrechina (Hymenoptera: Formicidae) of the continental United States. Sociobiology 9: 51-162.