One University researcher stumbled into some findings that may have a profound effect on the butterfly population in the Southeast.

Andy Davis – a doctoral candidate in the Warnell School of Forestry and Natural Resources – discovered that female to male ratios for Monarch butterflies east of the Rocky Mountains have been gradually changing in favor of the males.

Though accidental, Davis’s research findings are significant.

“I was working with someone from Virginia that had been capturing Monarch butterflies during the fall,” Davis said. “And out of 2,000 butterflies, maybe 35 to 37 percent of them were females, and I thought that was a really low number.”

Davis, who also conducts research on amphibians and migratory landbirds, said though the data on Monarch butterflies can’t conclusively prove a reason why the changes are happening, he has his speculations.

“There’s a parasite that they get with tiny little protozoan spores,” Davis said. “It actually affects females more than males.”

These statistics have led Davis to believe the parasite may have been gradually changing the sex ratio.

The research also shows the parasite is increasing in the Monarch butterfly population.

Climate change also accounts for another potential problem in the life cycle of the female Monarch butterfly.

When the butterflies migrate, the females don’t migrate to the winter locations as much “because temperatures have been changing and they need those cold temperature cues to tell them when to migrate,” he said.

Davis said he thinks the planting of tropical milkweed plant species might also be affecting the butterfly population.

“If the female sees those plants, they actually stop migrating,” he said.

This could have contributed to the lack of females showing up.

“These are merely speculations,” Davis said, emphasizing that statistics and research have yet to yield a definitive solution.

Regardless of the reasons, the decline in female Monarch butterflies means a hard time ahead for the species.

Monarch populations go through “booms and busts,” according to Davis, meaning the population goes up and down.

However, every now and then, there’s a big crash.

“Everybody always makes a big fuss over it because it decimates the population,” he said. “But the next year, the females come in and lay their eggs, and each female can lay up to 400 eggs.”

The next question: what happens when those females aren’t around anymore?

Davis suggested people try to protect the butterflies’ habitat needs at each stage of their life cycle to combat the growing irregularity in gender ratios.

“Just showing some good stewardship over this species would be beneficial,” Davis said.