Wasps/yellow jackets-> Slice a cucumber and arrange them in a single layer on an aluminum pan. The cucumber must be fresh – the pan MUST be aluminum. The cucumber reacts with the aluminum and gives off a chemical reaction.
DIY Natural Wasp Control : "slice cucumbers and lay them around your picnic or bbq; it keeps bees /wasps away. Learned this at the maple syrup booth at our state fair, no bees around. It was really amazing!