Danka and another entomologist, Jose Villa, wanted to find out how different groups of bees groomed themselves. They wondered: Do some bees clean themselves differently, or more often, than other bees?

So, they studied one group of bees that were all related to one another. These bees all shared a gene, or several genes, which give them greater natural protection against the mites.

Genes are passed down from a parent to child. In humans, they’re responsible for traits like eye and hair color. Certain genes can also control behavior that helps protect animals against disease.