This is a group of small beetles which have a somewhat unusual way of life. Both the adults and the larvae feed predominantly on moulds and they therefore live where these are to be found growing. They occur in cellars, outhouses and store-rooms where the humidity is high, and it is not uncommon for them to be seen in new houses, before the walls have dried out.
They sometimes also live in damp parts of houses that are otherwise quite dry. For instance, if a cupboard is standing up against a cold external wall, mould may grow on the wall itself and on the back of the clipboard, and this will provide food for the beetles and their larvae.
Damp corn, hay or straw in a loft may encourage the multiplication of these beetles, and their larvae may then appear in their thousands in the rooms below where they will be looking for a suitable place to pupate.
These beetles do not normally destroy anything, but now and again they may damage foodstuffs such as- dried fruit.
The only rational method of control is to make the environment so dry that the moulds on which they feed disappear.