A single bug couldn’t do much damage. Unless you’re scared of them, then maybe you’ll freak out. But as they say, there’s strength in numbers, and that’s when insects truly become threats that could cause great damage either by inflicting pain or causing diseases that could, in turn, result in death. The Great Plague in England in 1665 wiped out almost a quarter of London’s population in 18 months, with around 100,000 deaths. It turned out this was caused by rat fleas. It is a different story when these small critters are purposely used to cause havoc among the enemies, like when Japan dropped plague-infected fleas and cholera-coated flies in China, triggering a serious outbreak of the diseases during WWII.

Here are some other instances of weaponizing insects:

Scorpion Pots

When the Roman Emperor Septimius Severus wanted to capture Hatra, an ancient city in Upper Mesopotamia, at the end of the 2nd century, they were welcomed by scorpion bombs. Severus planned to gain control of the desert of Hatra that controlled the Silk Road— a large network of trade routes connecting China and the Far East with the Middle East and Europe. King Barsamia and the whole city were protected by 40-foot tall perimeter walls. The locals were also well-aware that their region was blessed with plenty of scorpions that could inflict painful stings and that they have venoms that could cause irregular breathing, slowed pulse, convulsions, and even death.

Scorpion from Blathur, Kerala. (Vijayakumar BlathurCC BY-SA 4.0, via Wikimedia Commons)

And so when the Romans reached the walls of Hatra, the defenders rained them down with earthenware bombshells with scorpions surprise inside, inflicting agonizing punishment in the form of arachnids. The Romans were stung on their legs, arms, and faces that were exposed. Because of this, Severus’ troops were held at bay, and it took his troops 20 days before breaking off the battle and retreating.