Hello
First of all sorry for my english, im spanish.
Im not sure if this can be consider exploit but i think is pretty useful to farm Dark Whelpling and Tiny Crimson Whelpling.
You have to go to Wetlands:
https://i.imgur.com/5hDt0.jpg?1
In this zone you will see 3 Ebon Whelp:
https://i.imgur.com/b7otd.jpg?1
Kill all and loot. When you kill all you will notice that 1 Whelp will respawn at the same time that other Whelp dies. You can kill Ebon Whelps with almost no downtime in that zone.
Happy Hunting.