A black wasp is another wasp in SLASH'EM, almost exactly the same as the yellow jacket, except that it does twice as much damage. Oddly enough, these have the glyph a, whereas the giant wasp has the glyph a.
Given that they appear in large groups in which they can do a fairly large amount of damage due to sheer numbers, one should be careful around these. In SLASH'EM, one should always use telepathy or the : command to make sure that the a around the corner is not in fact a black wasp, as opposed to a less dangerous yellow jacket or killer bee. In combat against these bees, Elbereth can be useful, even if simply written in the dust, just to make them scatter so you can pick them off one by one.