Bluetit & Parsley

Today I watched a bluetit pecking frantically at my parsley, then the little bird flew away with a sprig of parsley in its beak - quite a large sprig for a small bird.  Why?  I've seen bluetits on that plant in the past and assumed it was after insects, but this is the first time I've seen it take parsley away!  Anyone know? 

I have heard that starlings will take bits of herbs to act as an insecticide in the nest so do bluetits (and other birds) do the same?  Mags