You can make biopesticides at home from common kitchen items. In this project, you soak chili pepper and onion in hot water to create pest sprays. You then test how well these homemade sprays protect plants compared to a store-bought option.

Not all pesticides come from a factory. Chili pepper, neem oil, and onion are natural ingredients that may protect plants just as well as chemical sprays. To find out, you soak chili pepper and onion in hot water, mix neem oil with warm water, and spray each solution on a separate potted plant. A fifth plant stays unsprayed as the control. Every three days over two weeks, you rate leaf damage on a scale of one to ten. The results show whether biopesticides can match a store-bought chemical pesticide — or whether natural options fall short.