Flake Soil is a breeding substrate which has been fermented and composted and is suitable für beetle larva and other intervebrate animals like woodlouses and millipedes. It also serves very good as a substrate for egg deposition and as a place of retreat for adult animals.
Who mixes Flake Soil with other substrate (not recommended) or additives is acting at his own risk.
An adequate aeration by using Flake Soil in the breeding box is essential and very important as microorganisms and beetles/larvae both have to breeth oxygen.
High Protein Flake Soil should be fed to larvae within a month! If stored for longer time you should mix it several times. The longer it's stored the further the decay goes. After 3 months High Protein Flake Soil becomes mostly black soil. So still good to use.