Paul if your sister doesn't mind killing wasps, tell her to get some of that spray that shoots out a long stream of the spray, and armed with that, check her eaves and the tops of her windows around her house. The wasps are actively building their nests right now, and they need the nectar for energy. Spraying soapy water on the nests works, too. They won't start gathering insects and caterpillars until the baby grubs are born. Discouraging them from building their nests is the best way to keep them out of your yard.
It's amazing how many different wasps eat nectar for their sustenance.
I've grown hummer plants for years now along with putting out feeders. I've only found one plant that they prefer over a feeder. That's cypress vine, the one with the very narrow, ferns leaves. Be careful with this one, an annual vine, it re seeds readily and can become invasive. It's ridiculously easy to grow.
It comes in pink, red and white flowers. The Hummers like the red the best. As you can see from one of the pics, butterflies like them, too!
