Urbana house ants 2.0: Revisiting M. R. Smith's 1926 survey of house-infesting ants in central Illinois after 87 years

Quantifying the long-term ecological impacts of urbanization requires high-quality historical records and similar re-surveys over time. We replicated a survey conducted in 1924-1926 by Marion R. Smith of house-infesting ants in Urbana, Illinois, to examine how the house-infesting ant fauna and its control measures have changed over 87 years. We complemented residential sampling with pitfall, visual, and leaf litter surveys in the surrounding urban neighborhood and in three nearby forest fragments to characterize the ant fauna from which the house-infesting ants are drawn. In 1924-26, 12 ant species were collected in houses; the four most common were Tapinoma sessile (Say), Lasius alienus (Förster), Camponotus pennsylvanicus (DeGeer) and Solenopsis molesta (Say). In 2012-2013, we found eight species in houses, the four most common of which were Tapinoma sessile, Tetramorium caespitum (Linnaeus), C. pennsylvanicus, and C. nearcticus (Emery). Ant control measures have also changed dramatically, with the average amount spent per household in 2012-2013 nearly doubling (adjusted for inflation). We also found that the residential urban site had similar estimated species richness to one of the nearby forest remnants, demonstrating that the diversity of some arthropod groups can remain high in forested urban environments. Moreover, each site had a unique community of species, reinforcing the value of both small forest fragments and urban sites for supporting biodiversity. Our survey revealed changes in urban and house-infesting ant communities since the 1920s, but, in view of the global abundance of invasive ant species and the extensive changes in land use patterns in central Illinois, the relative similarity of the ant communities separated in time by 87 years was unexpected.