A small update: It’s summer 2021 and I’m still hoping to identify the critters that built these cocoons. Below are a couple of new stacks taken from the same specimens. If you’ve ever seen something like this before, please drop me a line! firstname.lastname@example.org
This first set is from a monarch butterfly.
Points of interest:
In summer 2019 I collected a number of road killed butterflies along a highway in the general vicinity of Ardoch, Ontario. Sometime later when I started photographing them under my microscope, I found these brilliantly coloured cocoons. Whatever made them used chewed up bits of the butterfly’s scales, and the variety in their appearance is due to the types and colours of scales selected. Extending from each capsule is what looks to be a dried membrane with a distinctive elongated diamond shaped tip. What I can see of the inside of them looks quite clean. I’ve been captivated by these tiny capsules ever since. They’re just so cool, and I’ve never encountered anything like them.
I collected my specimens that year in containers where they were exposed to each other for some time, so the critter responsible may have spread among my specimens. I can’t be sure which species natively host them, but I’ve found them on a Question Mark, a Painted Lady, White Admirals and Monarchs, all collected dead along the highway on the same days in the same location.
In 2020 I gained the ability to start photographing them on this scale. I haven’t found any signs of what eclosed from the cocoons. They may have escaped storage, but I didn’t notice anything. I still have the specimens, and I’d love to know more about them. If you recognize them, please contact me.