On Monday I could barely walk down the stairs. The day before I ran up a mountain and back down as part of the opening practice of our youth cross country ski racing team and my thighs were now telling me that I wasn’t in my 20s anymore. Athletics have a way of showing your age, but I was heartened to learn this week that I wasn’t alone. It turns out that butterflies have the same age old problem.
Recently, scientists in Sweden reported that the flight endurance of a small butterfly called the Green-veined White decreases with age. The Green-veined White (Pieris napi) is found across Europe and Asia, including the Indian subcontinent. Some scientists believe that the Mustard White, a woodland dependent species found here in the Northeast, is a subspecies of Pieris napi while others align it as its own species, Pieris oleracea. Either way, they are very closely related and look quite alike.
How do you test endurance in a butterfly? The scientists released individual butterflies 6 feet in the air and when they landed, they were prodded to fly again and again until they were unable to fly due to exhaustion. A simple stop watch yielded the total flight time. They tested three age groups that they raised in captivity. One group was kept in cages for 10 days and another was kept in the cages for 5 days. The third group was 1-day-old butterflies newly emerged from the chrysalis and roaring to go. Most of these butterflies probably only have an adult life span of about two weeks.
It didn’t matter if they were male or female, young and middle aged butterflies performed about the same, but by the time the butterflies were 10 days old they were over the athletic hill. I guess I must be about 7 in butterfly age. I hope that gets me through another ski season with the newly emerged.