Little black ants -- Argentine Ants -- are taking over California and the western U.S.
In fact, they're driving out native species of ants and killing off a lot of species. The charming if homely horned lizard of the western US is going extinct according to one study I read, because the bugs it eats aren't able to compete with this small but prolific pest. And little black ants don't provide enough nutrition, so species that eat bugs (sometimes a benefit to us) starve when black ants move in.
Little black ants are a particular problem right now for many people, because they multiply after rain. California has been in a drought for several years, and suddenly we've got rain, so we've got ants. If your house/apartment hasn't been invaded already, it will be!
I had a rude awakening when the wretched little black ants came in through my phone jack shortly before Christmas and got to a fresh-baked loaf of bread on my counter. They were swarming. Ugh.
This means war!
I generally get along with mother nature, but I draw a line at swarms of ants in my kitchen, bathroom, or other places where little black ants seem to congregate.
Keeping surfaces clean helps. So does calling an exterminator to spray the outside of your building. I won't do poison inside, because it's bad for pets, especially, and probably not good for us either.
Trouble is, Argentine ants are tough little buggers.
My preferred method is ant bait traps -- those enclosed tamper-resistant plastic disks that have poisoned bait inside. The ants carry the food back to the nest and sterilize the queen with it. So it takes a few days to work, but it means you won't have dead ant bodies, or poison, scattered in public areas.
Problem is that Argentine Ant colonies have multiple queens, so they're harder to wipe out. Plus they're all genetically related a lot more closely than natural, native species, since they all descend from a small batch of invading ants that came in on a load of cocoa (if I remember correctly) from a shipment from Argentina around 1910. Little black ants are all siblings, so to speak, and all part of the same supercolony. What this means is that even if black ants lose their queens, they'll just get adopted by another black ant colony, whereas normal ant species will treat members of other colonies as intruders and drive them off or kill them.
[Edit: Note -- I just googled and found some scientists are now challenging the "Supercolony" thesis. See my links section.]
Still, the spray outside/baits inside is the best trick I know.
Combat brand traps work best, as far as I can tell, although you'll occasionally get a colony that's resistant. Also, the "brand police" -- what my mom calls the invisible forces checking and removing your favorite products from the store -- seem to be all over Combat brand ant traps. Sometimes I'll still find them in Ace Hardware.
I've had to move to other brands. Some don't work at all-- there's one that only has one hole on the outside, and the ants never find their way in! Unfortunately I've forgotten the name. Raid bait traps work fairly well.
I have two home remedies to share in my ant-fighting arsenal. One is that pennyroyal tends to drive off ants, and is non-toxic, so it's the preferred herb of herbal remedy enthusiasts.
The other is that ants -- especially small ants -- won't cross lines of liquid dish soap. Why is this important?
Well, when I found out I was getting invaded, I made a little Great Wall of China across my kitchen counter across the ant trails in a semi-circle all the way around the wall they were emerging from. I did a thin arc of dish soap all the way around. At intervals along the line, like tiny forts, I placed the ant bait traps. So the only way the ants could cross the dish soap was by going THROUGH the ant baits, hopefully picking up bait along the way.
It seemed to work like a charm; the ants were gone in 2 days and *knock wood* haven't returned. I've removed the dish soap now but have some of the baits in out-of-the-way corners, just to make sure.
I have heard orange oil and other strong scents also work: the key is, ants find their way by scent, so strong-smelling liquids across their paths will break their trails.
Good luck and happy ant-hunting. I feel no remorse here, because they don't belong in this part of the world, and they're actually damaging to native species.
