This is not to say that P. rapae has left the garden. If anything, they are here in greater numbers than ever before. The little butterflies are flitting romantically in pairs over every plant in the garden, and even providing useful pollination services for my squash, cucumbers, and radish flowers. Over the month, I have really come to like them.
Until I did a bit more research.
I turned to “A golden book of butterflies; 187 familiar North American butterflies” (J. F. Gates Clarke, 1963). Now as a rule, scientists do like to avoid works over ten years old. However, it seems that the best field guides have all gone out of print in the past twenty years, and nothing comparably informative has been put on the market since. In fact, the Peterson’s guide to moths now fetches 80+ bucks used, and when I checked out of curiosity today, there were none available online at all. What does this say about our society?
Well, anyway, if you can get your hands on the golden book of butterflies (or ANY golden guide to insect life ever published), hug it tightly. Not only are they beautifully illustrated, they are the books that bridge the gap between children and scientific professionals. I believe one of the significant catalysts for my modern career was the collection of 60’s-era golden guides to wildlife that my parents wisely shelved alongside my childhood picture books.
Back to P. rapae. As many of my former students can attest, I have a real passion for the topic of invasive species. And it turns out, the small white, or “cabbage white” is a nonnative, introduced to Quebec in 1860. Apparently, it had covered all of North America within a century, almost entirely displacing its cousin, the mustard white. (The mustard white is identified as P. napi in the Golden book, but internet research indicates that P. napi is green-veined white, and there is scientific controversy over whether the mustard white, now known as P. oleracea, is actually a subspecies.)
I am interested to learn more about the modern-day distribution of P. oleracea, and whether exterminating P. rapae would help that original species to restore balance to native plant composition.