John Duarte brought in a large number of psocids he collected from a house. Their dead bodies are numerous in many areas of the house. The residents have a number of large bags of rice, which appears to be the source. There is, from what I understand, one large bag in the kitchen, with additional bags in the garage.
Apparently these bags of rice have moisture contents high enough to support fungal growth, and the booklice are feeding on the fungus, not the rice.
“The elevated moisture content (.13%) of commodities allows microorganisms (e.g., fungi) to grow and consequently to affect their properties [25–29]. Psocid infestations are favored when the moisture content of commodities is high, and psocids can feed on fungi” Source: Competition among Species of Stored-Product Psocids (Psocoptera) in Stored Grain