Today I tore apart a worm cage that had not been harvested in 18 months. It was the finest quality castings I have harvested.
This 3' diameter cylindrical "cage" of 1/4" galvanized wire mesh hardware-cloth sits on the edge of the garden near the hen house. Started with a few pounds of worms,its primary function is to handle what is cleaned out of the hen's nests. In addition, It gets fed horse manure on occasions, and is always covered in straw mulch.
The past 8 months only a little chicken manure has been tossed in. Little water has been added from my precious and stressed well. We are in an extreme drought, with little rainfall the past 15 months.
Today the cage was unwrapped. The top 6" had worm activity. All bedding and worms were placed in a wheelbarrow. A tarp was laid next to the pile to keep the casts "clean". I raked out about 1/2 cubic yard of the most beautiful looking 100% pure crumbly black castings I have seen! The cage was put back into operation.