In California, the pesty ant that invaded our kitchen was the Argentine ant (Linepithema humile). In Tucson, we had South American rover ants (Brachymyrmex patagonicus). Here in Illinois, our kitchen ant is a native species, Tapinoma sessile. At any given moment we probably have two or three wandering about our countertops.
The common name for this small brown insect is the Odorous House Ant, a reference to both the strong blue-cheesy odor these ants emit when crushed and to their habit of foraging indoors for food. They don’t normally nest indoors, though, they prefer to be outdoors where they can incubate their brood under a sun-warmed rock or pile of last year’s leaves.
The “pest” status of Tapinoma sessile has more to do with our human distaste for stray insects than anything the ant itself does. They do not cause structural damage, they do not transmit diseases, nor do they bite or sting. Instead, they wander about looking for crumbs. Nonethless, if you find the idea of a few harmless ants in your kitchen upsetting, they are best controlled by keeping a clean house, free of the little bits of food that attract them in.
photo details (all photos): Canon MP-E 65mm 1-5x macro lens on a Canon EOS 50D
ISO 100, 1/250 sec, f/11-f13, flash diffused through tracing paper