Craigs night 'n' time is great fly at night in New Zealand lakes as it does seem to represent the koura / freshwater crayfish which are a favourite food of trout. Often fished from the lake shore using a floating line and retrieved slowly in a figure of eight retrieve across the shallow bottom.This fly was tied with Pukeko (swamp hen) feathers but for commercial fly manufacturers a native bird feather is pretty hard to source so most are tied using dyed mallard duck feathers.
Again this is a fly that must swim correctly so we have to dispose of a lot of flies to get good ones hence the price reflects that.