Ants (Hymenoptera: Formicidae of Santa Cruz Island, California

We conducted ant surveys on Santa Cruz Island, the largest of the California Channel Islands, in 1975/6, 1984, 1993 and 1998. Our surveys yielded a combined total of 34 different ant species: Brachymyrmex cf. depilis, Camponotus anthrax, C. clarithorax, C. hyatti, C. semitestaceus, C. vicinus, C. sp. near vicinus, C. yogi, Cardiocondyla ectopia, Crematogaster californica, C. hespera, C. marioni, C. mormonum, Dorymyrmex bicolor, D. insanus (s.l.), Formica lasioides, F. moki, Hypoponera opacior, Leptothorax andrei, L. nevadensis, Linepithema humile, Messor chamberlini, Monomorium ergatogyna, Pheidole californica, P. hyatti, Pogonomyrmex subdentatus, Polyergus sp., Prenolepis imparis, Pseudomyrmex apache, Solenopsis molesta (s.l.), Stenamma diecki, Sn. snellingi, S. cf. diecki, and Tapinoma sessile. The ant species form a substantial subset of the mainland California ant fauna. We found only two ant species that are not native to North America, C. ectopia and L. humile. Linepithema humile, the Argentine ant, is a destructive tramp ant that poses a serious threat to native ants.