Jane and I live in Southern California, but we're both originally from New York. So when we moved here we were both thrilled with the winter climate, but we do pay a price. Once it gets brutally hot outside (usually in August), we seem to be invaded by ants, and we're not the only ones. Jane jokes around that all the homes in our neighborhoos were built on a giant anthill.
In the past we've purchased the "greener" ant deterrents, but they don't work all that well. We're not all that concerned with the insects, but we don't really want to add toxic elements to the environment, and we don't want to poison the birds who eat those pesky bugs! Jane was poking around the library the other day and she found The Natural Foods Garden by Patrick Lima (it's so old Amazon.com only has copies available thru their resellers!). Lima has a "vegan" rememdy which Jane is going to try next time we have unwelcomed visitors. The conconction is a mix of onion and garlic, minced, plus a tablespoon of cayenne pepper in a quart of water. Add whatever pungent herbs you have on hand... peppermint, coriander, cedar leaves or wormwood. Steep for an hour or longer, strain mix and transfer liquid to a spray bottle.
We've used a very similar mix for our rose garden. But we also add a bit of olive oil and dish soap (about 1 teaspoon each) to the liquid, and it really helps with the aphids. However, you really have to spray at least twice a week.
Anyway, it's worth a try.