Airtight plastic bags can help farmers protect their harvests without the use of harmful chemicals. These bags are designed to keep air out of crops in storage. Using them is a simple way to fight insects and keep crops fresh.     Ten countries in West and Central Africa are involved in a project to improve the storage of cowpeas, also known as black-eyed peas. Farmers can lose much of the harvest to insects called bruchids  , which grow from egg to adult in a few weeks and then lay forty to sixty eggs. They can destroy the whole harvest within months.     Farmers can sell their crops immediately. But selling at harvest time means more competition and lower prices.Or they can use pesticides   to kill the bugs. But a crop scientist Dieudonne Baributsa says, "They end up misusing or overusing the pesticide. In Nigeria, they have reported a lot of cases of death. They usually call cowpeas 'killer beans' in Nigeria."     Mr. Baributsa is a researcher at Purdue University in Indiana, America. The project is called PICS---Purdue Improved Cowpea Storage. He says the storage bags are thick enough that any insects already in the cowpeas willdie from a lack of oxygen. The lack of air will also help prevent the growth of bacteria that can ruin the harvest. The bags cost about two dollars each. Mr. Baributsa says that is not much, especially if it means farmers can wait long enough to get a better price for their crops. The bags are produced locally. Donors currently support the project, but the groups involved are working to build a lasting market for the bags because donation for the project will not lastforever.     A company based in the United States called GrainPro makes another kind of airtight bags. These are called SuperGrainbags. Phil Villers, the company's president, says storing a harvest safely not only helps farmers earn more money, but also reduces the amount of the harvest loss to insects, spoilage and mishandling. "What does not get wasted and eaten means it is possible to feed a hungry world," said Phil Villers. How does the name of "killer beans" come out?
The beans are poisonous by nature. People eat beans that are infected by bugs. Farmers use chemicals to kill bugs improperly. Bugs ruin beans within a short time.