Corpselouse Larva
Drops from Smorgas the Feaster. Though they are quite squishy while young, the bloodlouse will eventually grow hardened plates around its entire body. Critter type. Finally got this pet today. 2 months killing every day.
The 
is a pet drop from Smorgas the Feaster in Maldraxxus, requiring you to spawn and defeat this NPC repeatedly.
Guide awaiting review
Locate Smorgas the Feaster
Travel to Maldraxxus and find Smorgas the Feaster at 42.4, 53.4. Click the Bloody Lump meat in the middle of the area to attempt to spawn him.
Spawn the NPC correctly
If Smorgas does not spawn after clicking the meat, collect the small red corpselouse larva around the area without killing them, then drop them and wait for the small ones to turn yellow again before waiting a few more minutes for the meat to reappear.
Defeat and farm repeatedly
Once Smorgas the Feaster spawns, defeat him and loot the when it drops. Repeat this process as the pet has a low drop rate.
