How do I complete the Crispy Critters achievement?

Here's a video of the process:

The Stingers can spawn from Infernal Cocoons (for me 1 spawned for every 3 cocoons, roughly).

They also have a chance to spawn when you approach Hell Bringers, and if they do, 5 will spawn in a circle around you.

The best place I found to do this achievement was in the Tower of the Damned level 1.

• Start at the quest Kill Azmodan or The Second Heart and use the waypoint to travel to the Tower of the Damned.

• Run to the eastern side of the platforms and look for a Hell Bringer. If it's not there you can leave, reset it and go look again.

• Try to remove your weapon and damage Tormented Stingers to about half hp. If you don't it seems killing them doesn't count for you and you do not get the achievement.