It's a school day

At one time I was putting all P's banana skins in an MFB placed inside the covered kitchen waste bin with perhaps a view to making high potassium feed for the gh toms (it only half-heartedly happened). Anyway the  bucket was sinking lower and lower so I hoiked it out. On the top of the gloop, along with the brandling worms, were several  grubs about half inch long with a long tail. I'd never met these before, so googled before declaring outright war.  They are rat tailed maggots, the larvae/pupae of hover flies, so they're welcome to make their home in my compost gloop. You still learn things even at my age