In September, at a pull-off along Saguaro National Park East’s loop drive, I caught a glimpse of a beetle in flight. Large and shiny and yellow, it landed on a mesquite tree. I tried to get a better look, but before I could get close enough for a picture, it took off, its wings buzzing loudly as it flew away. Whatever this beetle was, it had extraordinarily good eyesight!
A month later, I was walking the Douglas Spring Trail at SNP East. I heard the distinctive buzzing of the same mystery beetle, and soon I saw it fly over the path and another thirty or so feet before landing heavily on a palo verde. I’m not sure it was so much my stealth but instead the cooler morning temperature that kept the beetle in its place, as this time I was able to photograph it.
The mystery beetle, as it turns out, is a Buprestid, more commonly known as a jewel beetle or metallic wood boring beetle. I had originally identified it as Hippomelas planicauda, but I realize now that it’s actually the closely-related Gyascutus caelatus. Both species are found in this area, and both seem to be covered in a bright yellow wax or powder that wears off after time. I’m curious if the yellow serves as a mechanism for attracting mates, or as a form of wasp mimicry, or both. It also makes sense that these beetles have such good eyesight, as well as fast flying abilities: they are incredibly easy to spot amongst the sparse palo verde limbs!
In December, I found another G. caelatus along the Douglas Spring Trail, this one much more docile and duller in color. I was able to pluck this one from the tree and hold it, and in doing so, more of its yellow coating came off. I now wonder if this powder might also serve as a form of protection from the sun.
Buprestidae is one of my favorite Coleoptera families, and it was a real treat to successfully find, photograph, and identify this beetle.
Bug Talk 
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