Dear C.:
I'm sorry for what you're having to deal with. You've already gotten fantastic ideas from the other mamas, so I just wanted to give you a little tidbit: Jars!
I've never had the problem that you are describing but I like to keep my house fairly bug resistant because I can't stand the thought of ANY bugs inside! So, EVERYTHING in cupboards is kept in sealed containers. The problem is, depending on how much you cook from scratch, that can get expensive. I cook from scratch a lot so I use large glass jars with screw on lids which are cheap (Target, Cost Plus World Market, Ikea, etc.) I recommend two sizes: a large size which can accomodate an entire bag of flour, sugar or masa and a shorter size which can contain an entire box of cornstarch or powdered sugar (the smallest size is pointless, IMO). Glass is best because it doesn't react with your food PLUS, it looks pretty if you ever end up living in a cupboardless place (like I did several times).
To start out, if you're on an even tighter budget than the price of the jars, remember there are plastic containers at the dollar store. Sometimes, too, you can use ziploc bags and tuck them inside large tins (let's say: Cream of Wheat, Cream of Rice, and oatmeal all together in one tin). This will keep the bugs away until you can finish purchasing your jars.
For the kids, I have five large plastic containers (that pour) for them to serve their own cereal. Glass is too heavy for them. I put these containers on the bottom shelf along with their bowls (and moved them up as the kids grew taller!)
I'd be very cautious about using toxic chemicals around food. I think mechanical solutions are best (obviously, after you've cleaned out what's already in there!) and natural methods of pest eradication/reduction (herbs, oils, etc.).
Eventually, you'll have a perfectly organized and clean pantry with everything in convenient, see-through jars (you can see what needs to be purchased) and, of course, any labeled canned goods that you purchase. Your new pantry will be a pleasure for you to work out of!
Best wishes,
M.