Cassus Roadside-Skipper

While this butterfly doesn’t look like much, what makes Cassus Roadside-Skipper (Amblyscirtes cassus) so special is that it has a very small, isolated range in the Davis Mountains of west Texas — the only place it’s found in the state. It’s more widely found in Mexico, Arizona and New Mexico.

As a biologist, this fascinates me. How did it get here? Did it arrive from poor adventurous souls that wandered from the main population, crossing miles of inhospitable desert to find a suitable spot? Or did it get stranded during the last ice age, at the end of the Pleistocene as the earth warmed and the forests retreated northward, leaving a little island of montane habitat where conditions permitted, and thus leaving a relictual population of Cassus Roadside Skippers with it? I suspect the latter.

Are there other relictual populations of Cassus Roadside Skipper? What about the Guadalupe Mountains directly to the north, or the Chisos Mountains directly to the south? Tending to give an answer of no, those mountains have historically been much better explored than the Davis Mountains, since both lie partially within national parks. But still, there’s always a chance. I also know nothing of the biology of this bug. Perhaps its requirements are not met in those mountain ranges.

What it all boils down to is that I know its name — Amblyscirtes cassus — and not much else. Without delving deeper, the answers to my questions remain obscure, like the butterfly itself. This subtle beauty is what so captivates me about the natural world. Some things jump out at you, yet others are easily missed. Whether it’s an Esenbeckia fly that you initially mistook for a mosquito, or a butterfly that doesn’t look particularly impressive, mystery and surprise abound. It’s the great privilege of those who choose to study it, to see this beauty firsthand.