These have a similar function to the Cherry Fluffs that spawn in KKD's instance, with the name format "Death to [username here]!" Instead of Kill...! . Once they find their target, they will explode and cause huge damage to anyone in the immediate area, similar to the Cherry Blossom Fluff in Zen Gardens.
When they get a more powerful hit it can go up to over 1000 damage but on average they do about 200 damage
They will start to appear more and more often past wave 45 and eventually (past like 130?), all roaches in the hive will be Death Roaches.
They also spawn during the "Bug Breakout" event in the Old Aqueduct.