The two "gut" keys for me are (1) Size: Tigers big, Blacks small. The largest Blacks will be only as large as the smallest Tigers. (2) Yellow spots. Blacks have double rows of yellow spots on the forewing, double rows of yellow spots on the body, yellow spots on the hindwing ... Exhibit A: Papilio polyxenes f If you're lucky to see the light through the wings, a third key is that female Tigers are really dark brown, not black. What's hard for me is sexing Black Swallowtails when they are ambiguous. I believe this one is male because of the solid row of yellow spots inside the blue, but he might be best called "metrosexual."

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Played a little. Will go back when I have more time. Thanks, Karen.