The tiny pile of debris appeared to be magically motivating across the rough surface of a freshly sawed oak stump.

On closer inspection, the debris, bits of white and black and brown all clumped together in a heap about the size of a pencil eraser, had a set of legs scurrying beneath it. A small face was visible peeking out along the bottom edge.

Behold the junk bug. Or garbage bug. Or even trash bug if you prefer.

Shambling across the stump, the bug looked like a homeless vagabond carrying all his possessions strapped to his back.

In reality, the junk bug is actually a cold blooded killer. Study the heap he carries closely. Those aren’t bits of leaves and dirt on his back.

The heap is made up of dead bodies.

The junk bug, also known as an aphid lion, is a voracious predator, common around the world. The bug is actually the larval stage of the green lacewing, a delicate and lovely flying insect.

Lacewings are often found at night near a porch light. Their bodies are a vibrant and limey green. Large eyes and big, diaphanous wings sporting an intricate filigree of veins call to mind fairies more than bugs.

But the larval stage, the junk bug stage, is decidedly uglier.

Scientists say junk bugs heap their kills on their back as part of an intricate camouflage designed to fool birds and predatory ants alike. Sometimes, the bugs add other bits of debris they find, such as small pieces of lichen or leaves. The camouflage likely helps the bugs hunt as well as hide. Aphids are a favorite target, as are the untended eggs of other bugs.

It is possible to grab the debris pile a bug is carrying and pull it off its back. Teasing apart the pieces, the insect carcasses are unmistakable. Most are a ghostly white. Heads and legs are easy to discern.

Junk bugs feed by stabbing soft bodied prey with a pair of sharp, horn-like mouthparts. The mouthparts are hollow. Once stabbed into a victim, the junk bug simply slurps out the soft innards of its prey like a kid sucking a milkshake through a straw.

Then the empty and lifeless husk is added to the gruesome pile and the junk bug scurries on, looking for his next victim.