My family went on vacation last month. We were home for maybe 2 days of August. We cleaned out our fridge before we left, threw out a few opened packages from the counter (like cereal and bread), and enjoyed our time away from home.
We loved our vacation but it still felt good to be home at the end of it. Sadly, our enjoyment was short lived. It wasn’t long before we found pantry moth larvae climbing up our walls, and a few days later we were being bugged by full grown moths. Egh. The next day we found weevils in our flour. Ah! Bugs everywhere!
The first step was to order moth traps. These use pheromones to attract the male moths to a sticky trap. The girls can’t get pregnant, and your moth problem ends quickly.
Next, we killed all the bugs we could find. We smushed the larvae, killed the moths, threw out all the food that the weevils could possibly have infested, and threw out shelf liners that could have eggs on them.
Cleaning is vital. We vacuumed out the cupboards then wiped them down with white vinegar. We bagged up the trash (and the vacuumed gunk) and took it outside, away from the house.
Over the next week we were vigilant. We frequently checked the kitchen for moths and weevils, and killed any we could find. A few moths got caught in the trap (yay!), but I think we caught it early enough that it didn’t become too big of a disaster. Haven’t seen a moth or a weevil in a few days.
This mess caused me to spend a few hours online trying to figure out how to keep this from happening again. The most effective thing I’ve found is to store grains, flours, nuts, and other food products in hard plastic or glass containers instead of the flimsy bags they are sold in. Bugs can easily eat through bags and cardboard. Plastic tubs and glass jars are much safer.
For long term storage, vacuum sealing and oxygen absorbers are highly effective. Most bugs need oxygen to survive. No oxygen, no bugs. We already store most of our long term stuff (including pasta, rice, and flour) in half gallon jars. We use a vacuum sealer to get most of the air out. We are going to start using oxygen absorbers (available cheap from the LDS church) to make it even more effective.
Some people suggest freezing. Freezing doesn’t destroy the eggs, so to be effective you have to freeze for 2-3 days, thaw for 24 hours, and then repeat several times to ensure everything is dead. Vacuum sealing is much faster and easier. Once the food is out of the freezer, it is of course possible for it to be re-infested. Again, not an issue with vacuum sealing.
Some people suggest including bay leaves in the storage container. I’m not an agricultural expert, but Utah State University has done some informal testing and is convinced that this is an old wives tale, and isn’t effective at preventing or correcting an infestation (see this page, or this PDF, or this other PDF). Either way, vacuum sealing is essentially free once you have the equipment and is a proven method of prevention and correction, so I don’t see a reason to use bay leaves.
The last bit of advice should be obvious, but I’m still a horrible offender: throw out old food! I have a habit of buying new ingredients for new recipes. These recipes are almost always flops, so I end up with bags and bags of strange foods in my cabinet. Take some time every few months to run through your cabinets and toss stuff that is expired or never going to get used.