Adefinite connection—a symbiotic relationship—between termites and bacteria exists. In particular, according to a study in 2013, more than 4,500 different species of bacteria live in termite guts! These bacteria help termites to extract nutrients from woody materials—although the bacteria don’t seem to have anything to do with the termite digestion (which may be genetically inherent in the termite itself). This may be of biological interest, but to the homeowner, termites often mean huge repair bills. After all, in the United States, the cost of controlling termites and repairing the damage from the creatures is about $2 billion per year.

For many years, rickettsiae and chlamydiae were thought to be viruses because they are very small and are intracellular parasites. They are now known to be bacteria because they possess both DNA and RNA, have cell walls similar to those found in gram-negative bacteria, divide by binary fission, and are affected by antibiotics. They can cause several diseases, including Rocky Mountain spotted fever (carried by ticks) from the bacteria Rickettsia rickettsii, and Q fever from the bacteria Coxiella bumeti.