A soil-dwelling predator mite (formerly known as Hypoaspis miles) used biologically to control fungus gnat larvae, thrips pupae and other soft-bodied soil pests.
Jeremy pronounces it 'stradiolipsis' and notes most people still call them 'hypos' or 'hypoaspis'. BuildASoil compost already contains them so buying is optional.
Discussed in: Ep 019