I use gallon-size freezer bags, but 15 pounds is rather a lot. I'd actually get a dedicated airtight container. I usually get bulk basmati at hippie dippy health food stores where the prices are absurdly low. Same with oatmeal, particularly steel-cut, you can buy the posh-ish brands like McCann's but the prices are out the roof and it's sometimes even less than a dollar a pound for something nearly identical, same with rice, bulgur wheat, freshly ground spices, star anise, pasta, etc.
You can get so many of this type of staples for so cheap that it's nearly free on a per-dish basis.
But basically for those giant burlap bags of basmati if you get the Royal White that's really popular or many of the no-name-in-English brands that show up in those ethnic groceries, don't even try to keep bugs out of them, just discard the packaging and put them in airtight storage. For something like five pounds of flour, I split between two gallon bags, but 15 pounds of rice is a pretty large amount. You could still use gallon bags or larger and divide it up, but it really deserves its own home.
I have had to keep all food staple items in storage like this for months because of an ant rampage that is only finally now nearly over after a counter-rampage of bait traps. As for the ants themselves, I recommend Terro liquid ant baits, one of the few of these products that seems to do more than dick. I've had other bait traps where they literally sat next to deliberately placed actual food and been completely ignored. It still takes a bit of diversion to get them interested in the baits, but when they do, they go absolutely nuts and consume them to the exclusion of actual food that won't kill them.
After a couple weeks past Vendetta, I still see ants, but they're almost exclusively on trails toward poison and back to their nasty little hive of evil. That bitch Queen is gonna get a dose of this some day.
