What's going on here? This photograph does the rounds pretty regularly, and it's usually described as showing the parasitization of a Cereal leaf beetle (Oulema melanopus) by Tetrastichus julis, a parasitoid wasp.

What's going on here? This photograph does the rounds pretty regularly, and it's usually described as showing the parasitization of a Cereal leaf beetle (Oulema melanopus) by Tetrastichus julis, a parasitoid wasp. They eggs are laid within the beetle, where the hatch and feed on it while it's alive. Eventually they burst out, killing the beetle.

Now, all this is true. However, the beetle isn't quite as full to the brim with parasites as it looks. The truth, believe it or not, is even stranger. There's just ONE parasitic larva in this photo, and you can clearly see it at the front. The rest of that squirmy mass inside the beetle? That's its fecal shield.

Yes, you read that correctly. A shield of fecal matter. Believe it or not, this is pretty common in leaf beetles. They deposit their fecal matter on their own backs. There, it acts as a deterrent to predators, prevents desiccation and provide camouflage.