True water bugs (Lethocerus americanus) belong to the order Hemiptera, while cockroaches are part of Blattodea. But despite this difference, it’s easy to understand why we use this term interchangeably.
Water bugs and cockroaches are different kinds of insects. The giant water bug (or ‘true’ water bug) is the largest ‘true bug’ and a member of the order Hemiptera.
True water bugs do in fact bite and their bites can cause damage, and even lead to allergic reactions. But the ones found indoors, such as Oriental cockroaches, don’t bite but they can still be quite harmful.