Like a lot of San Franciscans, ants are fickle and particular. They prefer a temperate day. They need water, but not too much, and prefer easy access to good food and they will follow in a long line as soon as anyone finds some.
So, much like last winter when, due to the drought heat and the dryness, ants were driven into Bay Area homes in search of water, milder temperatures and food, this winter the ants are back for the opposite reason it's too cold and wet out there.
As Stanford ant expert and sometimes Radiolab guest Deborah Gordon has said in the past, "They come in because of the weather, and they go out because of the weather."
And according to CBS 5, the parched ground and all the water consequently collecting near the surface where ants nest has caused another mass invasion.
"As all of the rain seeps deep into the ground, things will get better. But, in the meantime, the ants are being driven inside,” says one pest control specialist speaking to CBS 5.
Also, after four years of drought patterns and mild winters coming to an end, "exterminators say the insect problems may just be the beginning."
Of course having ants scurrying across your counters and walls is disgusting, but you may want to think twice before spraying chemicals everywhere, especially if you have pets or small children.
Exterminators can come and spray around the base of your building where the ants are likely entering, but Gordon, who's spent her life working with and studying the insects, is a lot more defeatist about handling the problem. Her study of California's Argentine ant problem at Stanford found that "the majority of Argentine ant invasions occur during winter rainstorms and summer droughts," and "it's not the pesticide that keeps ants out of your home, it's the weather."
Neither traditional chemical sprays like Raid nor natural herbal/orange sprays do anything but kill a few ants and put up a temporary barrier. Gordon recommends simply plugging up holes in walls, keeping pet food off the floor and sugar bowls covered, and making sure all surfaces especially those that you see ants traipsing across are kept clean with Windex. Ants leave a "scent" trail wherever they locate food, so humans' only defense from future invaders is to continuously erase those trails.
And, when it gets hot and dry again, expect that the ants will be back.