tramp ant

From tramp (“ship without a fixed schedule”) + ant, because they are often inadvertently carried on ships.

tramp ant (plural tramp ants)

1. Any of various invasive species of ant often inadvertently transported in soil with cargo on ships, trains, etc.
   • 2004, S. Bradleigh Vinson, Sean T, O'Keefe, Gordon W. Frankie, Chapter 6: The Conservation Values of Bees and Ants in the Costa Rican Dry Forest, G. W. Frankie, Alfonso Mata, S. Bradleigh Vinson (editors), Biodiversity Conservation in Costa Rica, page 67,

     The occurrence of highly invasive (tramp) ants (Passera 1994) is of concern, and Saks and Carroll (1980) showed that tramp ants could become abundant in disturbed areas while remaining uncommon in nearby undisturbed forests. Exotic tramp ant species have been found to produce major changes in abundance and diversity of invertebrate species in other regions (Lubin 1984; Zenner-Polania 1994).

   • 2011, Ana Eugênia de Carvalho Campos, “2: Emerging Urban Pests and Vector-borne Diseases in Brazil”, in Partho Dhang, editor, Urban Pest Management: An Environmental Perspective, page 21:

     Of the nearly 2000 known ant species in the country, almost 50 species are classified as tramp ants (Bueno and Campos-Farinha, 1999).

   • 2012, Eli M. Sarnat, Evan P. Economo, The Ants of Fiji, page 88:

     Monomorium floricola is one the world's most broadly distributed tramp ants, although little is known about the ecological impacts of M. floricola (Wetterer, 2010a).