Just discovered maggots and flies in my oldest dunder pit (beer keg). Yummy.
This pit was a bit over a year old, made with my best dunder (maybe 20 ferment cycles old), and had been coming along very nicely, went through all the stages others have described.
I had screened the top of the dunder pit pretty well (good enough to keep the maggots and flies inside the pit once they hatched out). But they must have laid their eggs through the screen to drop onto the dunder below. There is not a lot of them, so I guess they are recent arrivals. (The other two younger dunder pits seem maggot free so far, fingers crossed.)
Fortunately this pit was done anyway, and I got a whole bunch of molasses low wines sitting there for it. So I drained off and filtered the middle 1/3, and got about 13 litres. Very rich, complex, musty smell. I wouldn't call it 'nice', but it is not bad either.
Pretty excited about trying it. Been a long wait.
Questions for the experts on fully matured dunder:
1. How much do you use in the final spirit run? (as percent of boiler charge, 10%, 20%...?)
2. How do you store that precious middle 1/3 if you don't use it straight away? Just freeze it?