Ants (Hymenoptera: Formicidae) of Santa Cruz Island, California

Abstract

From the published records of only 10 ant species known from Santa Cruz Island (SCI), one might conclude that the diversity of ant fauna of this island is quite impoverished compared to the ant fauna of mainland California sites, where ant surveys typically collect more than 20 ant species (see Discussion). However, we present the results of four ant surveys conducted on SCI in 1975/6, 1984, 1993, and 1998, which greatly expand the known species list for SCI. This present synthesis was prompted by the discovery on SCI of the Argentine ant, Linepithema humile, a highly destructive tramp ant that poses a serious threat to native ants. Adrian Wenner first found L. humile on SCI in January 1996. A follow-up study by Andrew Calderwood and Emily Hebard in July 1997 found that L. humile occupied two noncontiguous areas, surrounding two dismantled Navy support facilities, that totaled less than 1% of the island (Calderwood et al. 1999).