Flea and Gnat

Flea noun - Any wingless bloodsucking parasitic insect noted for ability to leap.

Gnat and flea are semantically related in bug topic. In some cases you can use "Gnat" instead a noun "Flea", when it comes to topics like insect.

Gnat noun - Any of various small biting flies: midges; biting midges; black flies; sand flies.

Flea and gnat are semantically related in bug topic. You can use "Flea" instead a noun "Gnat", if it concerns topics such as insect.