This little butterfly is known as the Silver-bordered Fritillary (Boloria selene) in North America. It is also known as the Small Pearl-Bordered Fritillary in Europe. This butterfly is usually found in open woodlands or damp grasslands, and can be identified by its orange and brown pattern on the upper side of the wing and a row of silver “pearls’ on the outer-edge of the underside of the wing. The underside of the wing also has a colorful mosaic of white, orange, and brown marking.(2) I am not sure I would have used the term “pearls” to describe the white coloration along the outer-edge of the underside of the wing, but it does have distinct white spots.
There are 30 different species of butterflies in the larger family of butterflies known as Fritillaries. Fritillaries are further divided into the greater fritillaries and lesser fritillaries. Silver-bordered Fritillary belongs to the lesser fritillaries group and is one of 16 different species. An interesting thing about the Silver-bordered Fritillary name is that its scientific genus name “Boloria” means brushed foot and its species name “selene” is said to reference the Greek Goddess of the moon Selene.(1,3,4)
As I was watching this butterfly move about the field, I noticed that when it landed on a flower it would go through an interesting routine with its wings. It would hold them closed for a few seconds, then open them, then move them back and forth, then close them again. This prompted me to wonder what was the purpose of this movement.
It turns out this wing movement may have been related to the butterfly’s need for temperature regulation. Butterflies are cold-blooded ectothermic animals. What this means is that they do not have an internal way to regulate their body temperature. So they must warm themselves by obtaining heat from the environment. They do this in two ways: Basking and Shivering.(5)
Basking is the process where butterflies use the sun to warm their bodies. The butterfly will spread its wings and use them like a mini solar panel and absorb the warmth and energy from the sun. However, some butterflies are better adapted to use the bottom of their wings for this process. When butterflies used the bottoms of their wings to warm themselves it is called lateral basking.
Shivering is the other process that butterflies use to regulate their temperature. Shivering is just what it sounds like. Butterflies will shiver, or shake, their bodies to increase their temperature.
A butterfly’s optimal temperature is between 75 and 90 degrees.(6) Therefore, it is possible for a butterfly to become too hot. In that case, they will seek out shade to cool down.
This quick video shows the butterfly in action. If you turn the sound up you can hear the birds signing in the background. I wonder if you can you identify that bird by its song?
Learning about the temperature regulation process in butterflies was something new for me this week. I had observed butterflies in action before, but never questioned the reasons behind their behavior. This personal practice of questioning has become an important part of my naturalist journey. When I move into a place of curiosity instead of assumptions, many of the mysteries of the natural world begin to reveal themselves.
Have you learned anything new about the natural world lately? Please share in the comments below.