Male and Female Eastern Tiger Swallowtails
Date: Fall 2012
How can you tell the difference between a male eastern tiger swallowtail and a female of the species? I showed my students how to do this with monarchs but they asked this question when I showed them our state butterfly, the eastern tiger swallowtail, and I don't know the answer.
From this URL:
“The color of the eastern tiger swallowtail can vary. Males are yellow or yellow-orange with black tiger stripes. Their wings are bordered in black with yellow spots and there are black "tiger stripes" running across the top of their wings. Their long black tails have blue patches on them. Female colors can range from the yellow of the male to an almost solid bluish-black. Their wing span is between 3 5/8 and 6 ½ inches.”
From this URL which has nice photos:
“…females are dimorphic, some similar to the males and others are black with extensive blue scaling on the hind wings (photos 3 & 4; notice that you can see the tiger stripes on the third photo). Below: similar to the top side, mainly yellow background with bold black stripes; dark females have a shadow of the tiger pattern evident, at least in fresh individuals.”
Go to http://www.google.com and search on “Eastern Tiger Swallowtail” for more information.
Female eastern tiger swallowtails have more extensive blue on the hind wing than males, which have little or no blue. Dark form female tiger's look much like black swallowtails but still have the tiger stripes on the forewing, though they may be hard to see. Field guides, Kaufman, Peterson and others, clearly show the differences.
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Update: November 2011