An Anime Made Me Research a Corpse-Loving Butterfly!

A butterfly that helps solve murders in an anime? Naturally, I had to know if it was real.

Beautiful Bones: Sakurako’s Investigation

I first came across the term Lethe Diana while watching the anime Beautiful Bones: Sakurako’s Investigation (Sakurako-san no Ashimoto ni wa Shitai ga Umatteiru). As a die-hard anime fan and someone who loves mystery and crime stories, the strange elements of this anime immediately caught my attention.

One thing that kept appearing throughout the series was the mysterious Lethe Diana, often connected to murders or used as an important clue. Naturally, I became curious.

In real life, the Lethe Diana — also known as the Diana treebrown — is a species of brush-footed butterfly belonging to the family Nymphalidae. It is native to parts of East and Southeast Asia, including China, Korea, Russia, and Japan. With its dark brown wings and eye-like patterns, it honestly looks like something straight out of a gothic fantasy novel.

What makes this butterfly unusual is its diet.

Unlike the image many of us have of butterflies peacefully sipping nectar from flowers, some butterflies are actually tiny nutrient scavengers. Lethe Diana has been observed feeding on:

• Rotting fruit 🍌
• Tree sap 🌳
• Animal dung 💩
• Carrion (dead animals) ☠️

Why? Because decomposing materials contain salts, minerals, and amino acids that nectar alone cannot provide.

Think of nectar as dessert. Carrion and dung are more like vitamin supplements.

Despite the rumors, the butterfly isn’t tearing flesh apart like a vulture. Butterflies have a long tube called a proboscis that works like a straw, meaning they can only drink liquids. If they land on a dead animal, they’re simply absorbing moisture and dissolved nutrients from the surface.

Here’s another strange fact: male butterflies collect extra minerals and later pass some of those nutrients to females during mating. So a male butterfly hanging around a dead frog is, in a bizarre way, investing in future offspring.

Strange, right?

And Lethe Diana isn’t the only butterfly with unusual tastes. Some butterfly species have been recorded drinking from:

• Turtle tears 🐢
• Crocodile tears 🐊
• Human sweat 😅
• Mud and puddles after rain
• Occasionally even blood from wounds

Honestly, imagine tripping while walking (which I do all the time), scraping your knee, and suddenly noticing butterflies gathering around the cut. Wouldn’t that absolutely freak you out?

A creature we often admire for its beauty can turn out to have some surprisingly creepy habits — and that’s exactly why I found Lethe diana so fascinating.

Honestly, I never thought an anime would send me down a rabbit hole about a weird, slightly creepy butterfly — but here we are.