The assassin bug is a fascinating insect for many reasons, but the one that really stands out is its gruesome camouflage, which consists of the carcasses of its victims glued to its back.

There are around 7,000 known species of assassin bugs in the world, ranging from 4 to 40 mm in length and sharing the same formidable weapon – a sharp, curved, needle-like structure called a “rostrum”. It’s this rostrum that they use to stab their prey – usually other insects – and inject them with a poisonous saliva that liquifies their innards. When the victim stops moving, the assassin bug will start slurping away at its inside, until only the shell remains. That shell is used by some assassin bug species as camouflage, and some specimens have been observed walking around with a mound of insect carcasses glued to their backs.

Photo: Kurt @ Orion Mystery/Wikimedia Commons/(CC BY-SA 3.0)

But in order to get close to their victims, assassin bugs need to live up to their name and catch their prey off-guard. Some species are known for mimicking the subtleties of leaves that move when the air rustles them, and making no sound when approaching unsuspecting insects. Once in range, the assassin bug pounces on its victim and impales it with its rostrum. As the digestive enzyme is pumped through the rostrum, it takes up to 15 seconds for the prey to succumb to its grim fate.

Scientists can’t yet explain how exactly assassin bugs are able to glue the shells of their insect prey to their backs, seeing as they don’t seem able to reach their backs with their limbs. What is known is that the carcasses are glued onto its back using a sticky secretion.

 

Apparently, this gruesome camouflage helps some species of assassin bugs to more easily approach unsuspecting victims, by blending into the surroundings more easily as well as by adopting their scents. This exoskeleton also works as armor against the bug’s own predators, like geckos or jumping spiders.

“What happens when a gecko tries to capture one of those, is it might actually end up with a mouth full of ant carcasses rather than a juicy assassin bug,” biologist Christiane Weirauch told WIRED Magazine.

 

In an experiment designed to test the camouflage against jumping spiders, which are known for their great sense of sight and their poor smell, both “naked” and camouflaged assassin bugs were placed in glass cages with the spiders. results showed that the spiders attacked the naked bugs roughly ten times more often than the masked ones.

The macabre disguise of assassin bugs is just one of the many types of natural camouflage we have featured on Oddity Central. This dead leaf butterfly, and this moth mimicking flies feasting on bird droppings, are among the most interesting examples.