The bags are called PICS bags - short for Purdue Improved Cowpea Storage. They cost $2 each. Baributsa says that's about the same as pesticide treatment. And it's a fraction of what farmers can earn from an intact bag of cowpeas, especially when they can store them until after harvest time, when they can get a better price.

Not just any bag

But he cautions that not just any plastic bag will do. Liners for salt or sugar bags sold in African markets, for example, will not work.

"Those are low density, so they are very permeable to oxygen," Baributsa says. "So, if you put your cowpeas there, they will be destroyed because the insects will still access the air."

PICS bags, on the other hand, are completely airtight.

Building a sustainable market

And they are produced locally. Along with partners all over West Africa, Baributsa is working to create the entire supply chain for PICS bags, from manufacturers to retailers.

Building a market is critical, Baributsa says, because donor support for the project will not last forever.

"Many development projects give the farmers the bags," he says. "And then once the project ends, the farmer cannot find the bag on the market. We feel like that is not a sustainable approach to development."

A sustainable approach means building demand, too. So the project is advertising on the radio and through mobile phone videos in local languages.