I understood it to mean insects, and was confused that the article's body talked about bacteria. Like, is this a usage of "bug" I'm not familiar with? Dictionary results talk specifically about insects (and about surveillance electronics)... Ok, Merriam-Webster's 3a here says it can refer to a microorganism of indeterminate nature: https://www.merriam-webster.com/dictionary/bug

I still think an editor choosing the title should have realized that "insect" is the more common interpretation, and should have chosen a less misleading word.