Q. My grandmother insists that the small, scurrying insects in her kitchen are not cockroaches, but that they are waterbugs. Aren’t they the same thing, or is there such a thing as a waterbug? These look like cockroaches to me.

A. There are plenty of different insects that live in water, and some are called water bugs, but unless your grandmother has a pond in her kitchen, I think her waterbugs are really cockroaches. Waterbug is a fairly common nickname for a roach. Some people choose to use the term “waterbug” because of the negative connotation of the words “cockroach” or “roach,” and some because that’s what they’ve always heard.

When people refer to cockroaches as waterbugs, they’re not always even talking about the same type of cockroaches. And of course, there are regional differences. In most cases, it’s the large, black oriental cockroach that is referred to as a waterbug. But in some areas, American cockroaches are called waterbugs. Sometimes people use the term waterbug to refer to cockroaches that get into their homes from outside. Both American and oriental cockroaches do live around building foundations and can find their way inside.

Just yesterday, I heard a gentleman talk about the large waterbugs that get into his home at certain times of the year. From the description, we determined that he was talking about American cockroaches. Many years ago, I was at a lanai party in Florida where American cockroaches kept gliding over the heads of guests to land on the walls. Somewhat disconcerting! People were whispering about cockroaches, but the guest assured everyone that they were not cockroaches, just waterbugs. In another case, I pointed out to an apartment resident the tiny, newly hatched German cockroach nymphs in her dishwasher. “No,” she said, “I do have cockroaches, but those are waterbugs.” Yet another type of cockroach given the name waterbug.

It’s easy to understand how cockroaches got the name waterbug since all cockroaches are tropical in origin and prefer high temperatures and high humidity. Given a choice, they will choose to hide in damp areas rather than dry areas. The most common cockroach in homes, the German cockroach, has an association with water. It is found most often in kitchens and bathrooms. Both American and oriental cockroaches can find their way into homes from nearby sewer systems. In homes, the oriental cockroach is found on the lowest levels, in basements or crawlspaces where humidity is highest.

In an Internet discussion about this very question, one writer said that he knows the difference. Waterbugs, he said, come up the drains from the sewers and there’s not much you can do about them, but roaches come from filth and are a sign of a dirty home. Waterbugs, he said, come and go, but roaches multiply quickly and infest your house. Fact is, they’re all cockroaches. They all need food, water, and shelter in order to survive. If you provide it, they will come.