I recall when visiting a European organic (not sure if it was biodynamic --- would a biodynamic farm have a slurry pit?) farm in 1984 I saw these astonishingly large larvae (I believe they were fly maggots) exiting a large, partially below-ground, slurry pit. After growing by consuming the slurry, they were leaving and moving away from the liquid manure, I assume to pupate in the soil. No one on the farm gave them a second glance. I assume therefore that they were beneficial or at least not pestiferous. This was in either Germany or Switzerland. Would anyone know their approximate identity? To what family of diptera they might have belonged?
Since nettle water and other fermenting plant extracts smells remarkably like liquid hog manure (a point not often emphasized, let alone mentioned, in popular biodynamic literature!) I assume certain flies would be attracted to lay eggs in the concoction. I keep my nettle water loosely covered during fermentation. I've had no flies developing in it. The odour is not all that bad. I live in an urban residential area on a 25-foot wide lot. My neighbours don't complain about, or perhaps even notice, the odours of which I'm acutely aware. There is quite a lot of work being done currently on using the (tropical and subtropical) black soldier fly larvae (Hermetia illucens (L.)) to help reduce organic waste. See: http://www.ads.uga.edu/annrpt/1995/95_311.htm. I don't think this was the species I saw. Vere.
