Catching Butterflies for Fun (and Science)

A Cabbage White Butterfly (Pieris rapae) Photo by Frederick Gralenski
A Cabbage White Butterfly (Pieris rapae) Photo by Frederick Gralenski

Does spring fever give you the urge to frolic in fields and chase butterflies? If so, grab a net and go for it. If anyone gives you a funny look, tell them you are doing important scientific research.

Scientists with the Pieris Project are asking people all over the world to collect cabbage white butterflies. This small, delicate-looking butterfly is one of the world’s most successful invaders. The cabbage white originated in Europe, but has spread to most continents and adapted to a wide variety of environments. Scientists want learn how this world traveler and agricultural pest pulled it off. To figure it out, they are enlisting the help of citizen scientists armed with butterfly nets.

The cabbage white butterfly (Pieris rapae) is small, only 1 to 2 inches in wingspan. It is mostly white, with a dark gray tip and one or two spots on its front wings. The rear wings can be white, grayish-white or pale yellow. The cabbage white is one of the most common butterflies in North America. In fact, in the course of writing this I have seen at least 3 of them flutter through my backyard.

As a caterpillar, this butterfly feeds on plants in the mustard family, which includes many popular vegetables such as cabbage, broccoli, kale and Brussels sprouts. Scientists believe this insect was accidentally introduced to the East Coast around 1860 when it stowed away in some cabbages brought from home by European immigrants. Then it hitched a ride on the railroad, hiding in vegetable cargo, and in about 40 years it had spread all over North America.

Scientists with the Pieris Project are asking citizen scientists to catch these butterflies and send them to their lab at the University of Notre Dame. There, researchers will analyze the butterflies’ DNA to learn more about the genes that allow it to invade new environments. They will also study how the butterfly has changed as it spread across the globe.


So far, citizen scientists have sent in butterflies from 25 states and ten different countries. Even Mesa County has contributed a sample! Josh Jahner, a Colorado Mesa University alumnus who is now studying entomology at the University of Nevada, Reno, collected a few cabbage whites in Orchard Mesa last summer when he drove through the Grand Valley.

But Sean Ryan, founder of the Pieris Project, says that they are hoping to increase participation this year and that more samples from Mesa County and Colorado are welcome. Ryan is Ph.D. student at the University of Notre Dame and very enthusiastic about getting citizens, young and old, involved in science. He and his team are even developing teaching modules so that teachers can incorporate the Pieris Project into their science curriculum.

Sadly, participating in this science project does involve killing some butterflies. Because they are agricultural pests, cabbage whites need to be dead before you ship them across state lines. You can kill them humanely by placing them in a container in your freezer overnight. But don’t be too sad- these butterflies are abundant and have short life spans even if they don’t participate in this project. And a cabbage white in the net may mean healthier broccoli plants in your garden this summer.

To get all the details on the Pieris Project, as well as everything you need to know about identifying, catching and shipping cabbage white butterflies, please visit their website: Then grab your net and get ready to chase some cabbage whites!

This article originally appeared in edited for in the April 19 issue of the Grand Junction Daily Sentinel

Catching Butterflies for Fun (and Science)