Why are Swallowtail Butterflies called "Swallowtails"?

Question

How did they get that name?

Answer 1

1st question's answer: Cause their hind wings extend into a tail.

2nd question's answer: By the odor they release.

        Good luck!

Answer 2

They have the long tails on their hindwings, something like the forked tail of the bird called a swallow.  Same thing for the swallow-tail coat sometimes worn by men at weddings or other formal occasions.