Rare Half-Male, Half-Female Butterfly Found At Museum

A half-male, half-female butterfly is fluttering in the spotlight now that a museum volunteer at Drexel University has spotted its unique coloration. The Lexias pardalis butterfly recently emerged from its chrysalis when Chris Johnson, a retired chemical engineer who was volunteering at the exhibit Butterflies!, caught a glimpse of its new wings.

"It slowly opened up, and the wings were so dramatically different, it was immediately apparent what it was," said Johnson. 

The butterfly’s right wings are characteristic of females of its species—brown and freckled with yellow spots—while the left wings are typical of males—dark with iridescent blue-green margins. 

To verify Johnson’s find, the museum called on Jason Weintraub, an entomology collection manager and lepidopterist. Weintraub confirmed that the butterfly was indeed half-male, half female, and said it has a rare condition called bilateral gynandromorphy.

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Gynandromorphism results from the disjunction of sex chromosomes, a developmental hiccup that occurs early in development during the division of chromosomes. The result is an organism that has both male and female characteristics neatly divided down the middle. 

^{Photo J.D. Weintraub/ANSP Entomology}

Part of the rarity of this butterfly is that is was spotted live. “In most cases, such specimens are ‘discovered’ in museum collections by a researcher who is carefully examining reproductive organs of insects under the microscope and stumbles across a specimen with both male and female characteristics,” said Weintraub.

But the butterfly is more than a mere curiosity. Genetic anomalies such as these can aid scientists in learning more about animal development and biology. In recent years, there have also been reported cases of dual-sex chickens and zebra finches. 

According to the academy’s staff, the butterfly was preserved and pinned, and will be on display at the Academy of Natural Sciences at Drexel University from Saturday, Jan. 17 through Monday, Feb. 16.

^{Academy volunteer Chris Johnson (left) with entomologist Jason Weintraub (right) and the preserved Lexias pardais. Credit: Doug Wechsler/VIREO}