The problem increases following warm summers. The commonest psocid found in households is called Liposcellis bostrychophila. Virtually all the psocid related complaints involve this single species. This has most recently been confirmed by a KCL survey of flour produced in 2000. Freshly bought flour is highly attractive to psocids and if they are present in the kitchen will rapidly colonise the new flour bag.
Most householders throw away infested products and clean cupboards before restocking.
As with all foods, it is important to store as recommended and to use products before the best before date. Dry goods, particularly those used intermittently, are commonly found in kitchens well after the expiry date and may provide a focus at the back of a cupboard in which psocids can persist.