Tachysphex nigerrimus, also known as the black cockroach hunter, is a species of wasp in the family Crabronidae.

[2][3] This species is known as the black cockroach-hunting wasp or black cockroach hunter in English, and in Māori as ngaro wīwī (written "ngaro wiwi", without macrons, in older sources).

[5] This name is used for all the New Zealand hunting wasps in the families Eumenidae, Pompilidae, and Sphecidae, such as Pison spinolae and Priocnemis monachus.

[8] The female T. nigerrimus hunts for native cockroaches (such as Celatoblatta or Parellipsidion), which she stings, paralysing them, and drags or flies them back to her burrow.

[1][7] T. nigerrimus is endemic to New Zealand and is found throughout the North, South and Stewart Islands.