To find this mob in-game, use BACKSPACE to open the World Search window, then enter Needle Cactus in the Search field and click "Search". Remember, the field is case-sensitive and must be entered exactly as shown.
A Needle Cactus has a 50/50 chance to re-spawn as a Needle Cactus or Flower Cactus. Since a Flower Cactus or Fruit Cactus re-spawns as a Fruit Cactus or Flower Cactus, once a Needle Cactus re-spawns as a Flower Cactus the Needle Cactus population is permanently reduced until the next server re-boot. This makes the Needle Cactus very rare and hard to find.