Starcraft 2: 8 Medivac drop

[Mutant Sheep]

Question for you: What is the Zerg build that Terran mech absolutely hates to be up against in the middle game? I've been trying to get back active, but mech just dominates me in ZvT.

LINGS. LINGS LINGS LINGS. (Roaches and burrow is always fun against mechanicals, I think. They spam scan and you have armored units. Their siege tanks be no match! /knows nothing of what he speaks)