The 18-month study conducted in 69 households between Redwood City and Gilroy found that the heaviest ant invasions occurred during winter rainstorms and summer droughts. Folk wisdom has tended to link ant invasions with wet weather, but the study is the first to examine and test that suspicion. Researchers also discovered a grim bit of news for anyone trying to drive ants out of their kitchen. The seemingly invincible Argentine ant, an exotic invader that was first noticed in California in 1908 and has overpowered all other species in the flatlands as far north as Chico, is the study's subject. They treat separate nests as if they are all part of one big happy colony.
Most ants spend a lot of time fighting their own species.
Another reason for the hardiness and durability of Argentine ants is that their nests contain multiple queens and males, a fact of biological life that enhances a colony's chances for survival, the Stanford study found. Simultaneously, they gathered weekly temperature and rainfall data from six meteorological stations. The researchers found that applying various foreign substances to ant routes did have some effect in reducing ant populations during unusually heavy invasions. But all of the remedies had about equal effects. We found no indication that certain pesticides are more effective than others . . .