Bruce Schneier on Woodland Ants
Shamelessly lifted from Bruce Schneier's Crypto-Gram mailing list. I think this is from the March 2003 mailout.
"The woodland ant (Pheidole dentata) survives in areas dominated by fire ant colonies, even though the fire ant colonies both tend to be up to one hundred times larger and make lousy neighbors. The woodland ant's trick is counterattack: it has a permanent population -- about 10 percent -- of warrior caste ants who do nothing but patrol with the worker ants. Whenever any of these ants sees a fire ant, they rush it, get some of its smell on themselves, and then run home, laying a scent trail. They immediately alert the hive, and any other workers and warriors they encounter along the way. A huge force of these woodland ants arrives shortly, kills the offending fire ant, and then spreads out to search for survivors. The warriors will keep circling the area for hours, looking for and killing any other fire ants they find. By throwing the maximum possible effort into this counterattack, the woodland ants ensure that no fire ants get back to their hive with accurate information about the woodland ants' whereabouts."
Security through extermination of the curious. Kind of a useful thing to know.