Mating Sexually Dimorphic Tiger Swallowtails

Subject: Mating Swallowtails
Location: New Cambria, Missouri
July 25, 2014 3:45 am
I took this photo yesterday of these two different (species?) of Swallowtails mating. Is this common? Can it result in viable offspring or a hybrid butterfly?
P.S. LOVE this website. It has been very informative.
Signature: Denise

Mating Tiger Swallowtails
Mating Tiger Swallowtails

Dear Denise,
The Tiger Swallowtails in your image are actually the same species.  The dark individual in the image is the female.  Though most female Tiger Swallowtails are yellow with black stripes, a small percentage of female Tiger Swallowtails are known as dark morphs, and even though the bold tiger striping is not evident, close inspection reveals a black on black striping pattern.  There are also examples of transitional coloration that fall between the light and dark morphs, and even more unusual are hermaphroditic gyandromorphs that contain traits of both sexes and which sometimes exhibit a combination of light male attributes and dark female attributes.  One final note, even without considering black morphs, Tiger Swallowtails are a sexually dimorphic species.  Female Tiger Swallowtails have blue dusting on the hindwings while male Tiger Swallowtails lack the blue coloration.  We are highlighting your posting on our scrolling feature bar. 

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