The Malaysian Assassin Butterfly
Geez, have one butterfly species mutate into a magic-sensitive version with distinctive skull-and-crossbone markings, a stinger, and hallucinogenic venom and then suddenly everybody wants to go Full Metal Pulp Adventure on it. To begin with, the stinger is demonstrably incapable of piercing human skin. Seriously, some very, very unsavory people with a strange sense of drama conducted some rather immoral human testing along those lines. Second, sure, if you grind up a bunch of the butterflies you’ll end up with a paste that will make you see things. But you’d have to grind up a lot of butterflies to get the effect. It’s cheaper to go out and score some LSD, by far.
On the other hand? Having a butterfly species that only appears in areas where there has been intense magical activity recently is often useful. Particularly since they seem to suck up potentially harmful residual magic in the same way that a sunflower sucks up heavy metal contamination. This makes them simultaneously problematical and highly useful: on the one hand, having skull-and-crossbones butterflies wandering around makes it more difficult to cover up the fact that magic exists. But on the other hand, having them eat any stray magic still lying around can help cover up the fact that magic exists. And on the gripping hand: maybe you can call them moths, or something. Moths are pretty much the go-to explanation for any kind of weird, large-winged bug…