Athens News Matters: Climate Impact on Butterflies

May 14, 2021


Credit TAMU

The problem with doing a story about butterflies, as opposed to, say, birds or bees is that - well, you can’t really hear butterflies. But trust me when I say that butterflies are more abundant. At least in the South. At least for now. But, as University of Georgia agroecology professor Bill Snyder says, it’s not quite that simple.


“So the main things that seem to be happening with these butterflies was a complex pattern that differed across the United States.”


Let’s pause for a minute to unpack this because it IS complex. Butterfly populations vary depending on climate, and climate differs across the country. So both seasons and regions have an impact on butterflies. 


“So in the southwest, and the western US where we've had these increasingly intense droughts and periods of greater heat, butterflies seem to be declining relatively strongly.”


And in the southeast? 

“In the southeast, rainfall has stayed pretty strong, temperatures haven't increased quite as much. In those cases, butterflies seem to actually be increasing.” 

So, as Snyder says, we’re lucky in the southeast. BUtterfly populations are increasing, and they seem relatively healthy. But that might change, because - well, summers in the southeast can be pretty brutal. Here’s Snyder’s colleague, Michael Crossley, a postdoctoral associate.

"Winter, that minimum temperature, that's gonna have an impact, the summer that maximum temperatures can have an impact. In the spring in the fall, that precipitation can be really important. We know that insects and plants can have sometimes different responses to a warming spring."

It’s probably not a huge shock to hear that there’s a connection between butterfly populations and climate. But the nuances of that crucial connection can be fascinating, according to Snyder. In a way, that connection is less about monarchs and swallowtails than it is about … milkweed. And Marigolds. 

“Butterflies, of course, are dependent on their plants. So the caterpillars need to feed on plants to be able to grow and develop, and the adults, you know, feed on flowers for nectar.”

And while there has been a *recent increase* in butterfly populations, experts like UGA Entomology Department Head Kris Braman are still concerned about their decline.


“There has been some concern over the last several years about lower butterfly populations in general...loss of habitat is I think one of the biggies. So that's an important factor, and one of the reasons why we really try to promote people adding their own pollinator space, not just for the bees, but for the butterflies as well. "

And like everybody else, I want to attract more butterflies to my yard, so I asked Kris Braman what plants I need to do that. 

"So for the swallowtails, it might be parsley, or bronze fennel, for our beautiful little Gulf fritillary, it could be a plant called maypop or passion vine. "