Answer: The ants aren't eating the flowers, the aphids are. Ants hang around with aphids and (this is gross) consume their sweet excrement called "honeydew". So what you need to control are the aphids. You can try insecticidal soap, or even a strong shot from the water hose. Most wisteria trees have a weeping form naturally, they don't need a support system. If your branches seem to be breaking, you can tie them to more sturdy branches with small pieces of nylon hose.
Q&A Library Searching Tips