Slugs may be the bane of a gardener’s existence, but during World War I they saved the lives of soldiers. Mustard gas attacks were a big threat during the war—the poison would painfully, and sometimes fatally, burn the skin, eyes, throat, and lungs. When America entered the war, the Army wanted to find a way to detect the gas before it reached strong enough concentrations to cause problems. They tried using various animals and insects, but to no avail—they were susceptible to the gas too.
Then naturalist Paul Bartsch came to the rescue. He was a curator at the Smithsonian’s Natural History Museum, and though his specialty was mollusks, he was interested in creatures of all varieties. He remembered that a few years previous, some garden slugs (Limax maximus) he was studying in a box escaped. He found them in the furnace room and noticed that they were reacting to the low levels of gas emitted by the furnace.
So when the need for a mustard gas detector arose, Bartsch decided to test out the slugs. He found that the slugs were really sensitive to the gas and could sense it at a dilution of 1 per 10–12,000,000, whereas humans detected it at 1 per 4,000,000. On top of that, the poisonous gas didn’t kill the slugs, because they could protect their lung membrane. Bartsch told the Army about the results, and they quickly adopted the slug method of mustard gas detection.
Read more about the role of slugs in WWI here or here. Or read more about Paul Bartsch here. You can also find contemporary news stories about Bartsch in Fold3’s Newspapers collection, or find more stories from the war in Fold3’s World War I collection.