I've looked through the pictures (particularly yellow jackets but those seem to be a lot more yellow than these guys) and can't find a match. These are swarming around the front of our house (daytime only) where there are lots of nectar plants and associated insets. They are a little over an inch long, exactly 3 yellow bands on a black abdomen. The very tail end is all black. The head and thorax aren't quite as light colored as shown (dark brown maybe?) since the flash went off when I took the picture.

Larry

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