Beetles to Blister By

Feeling itchy? We all know about plants like poison ivy and stinging nettles as potential irritants, but until this morning, I had not heard a thing about blister beetles.

As you can see from this photograph, blister beetles are seriously tough insects. As their name implies, they can cause severe blistering – serious enough to cause severe illness when they are accidentally eaten by livestock.

The cause is a substance called cantharidin, which is present in spanish fly – the purported aphrodisiac taken from a species of blister beetle. What good is it to get hot and bothered if you start to blister? Most potential sexual partners don’t respond well to a rash. If ingested, it causes painful genital swelling.

These beetles do more than just give people bumps, however. Some species tackle bees for a living, waiting on a flower for a bee to come by, then leaping onto the bee and riding back to the colony, and eating the eggs and larvae there.

There has been much speculation of whether cantharidin could be used for murder. It would be grisly, a blistering from the inside out. One case of manslaughter using the substance took place in London decades ago, as a man gave candy laced with the substance to a woman he hoped to seduce. She, and another coworker who ate the candy, died in terrible pain within a day. He did not get what he was looking for.