Hmmmmm

So if the bug is a Fungus-eating Ladybird (Illeis galbula) and the 'slug-bug' is a Fungus-eating Ladybird larva, what's the relationship between these two?  Of course, one or more of my assumptions may be wrong and I'm fine with that, but I really would like to know what what happening here (at the risk of someone explaining the facts of bug life to me!)