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

Introduction

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.

Synonymy

Paratrechina pubens Forel 1893

Distribution

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 N. 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 N. 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 N. pubens into Palm Beach County.

Florida distribution

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 N. 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 N. pubens, frequently observed in insect species."

Description

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.

worker

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 N. pubens, total length 2.0 to 2.5 mm as compared to 2.6 to 3.0 mm for N. pubens (Trager 2004 personal communication). Deyrup et al. (2000) state that N. 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).

Prenolepis imparis with "hour-glass"shaped alitrunk

Life Cycle

Little is known of the N. pubens life cycle. During a cold winter morning in West Palm Beach, Florida, one de-alate 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).

workers tending brood

queen and workers tending larvae

worker, lateral view

worker, frontal view of head

acidopore at apex of gaster in worker

male, lateral view

Foraging and Feeding

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.

ants on bait

Nest Sites

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.

nest

Pest Status

Most of the reports of N. 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.

Management

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.

Selected References

Authors: John Warner and Rudolph H. Scheffrahn, University of Florida
Photographs: R.H. Scheffrahn and J. Warner, University of Florida; F.J. Santana, Extension Entomologist, Sarasota County; and Tim Linksvayer, Carleton College
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-284
Publication Date: March 2003. Latest revision: August 2010.
Copyright 2003-2010 University of Florida

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