Even water or spots with increased moisture can be detected by insects.

Vertebrates such as rodents or birds may also feed on stored products. But it is easier to keep these pests away by a good structural design of the storage building because they are much larger and usually need an additional source of water.

Microbial deterioration of durables usually occurs if the product was not sufficiently protected from rain or moisture or after an attack by insects, mites or vertebrates that increased the moisture content. Mites already require higher moisture contents and often occur together with storage fungi. Because many stored product fungi such as the genera Aspergillus and Penicilium are known to produce mycotoxins, a visible microbial infestation generally renders the stored product unsuitable for human or animal consumption. Mycotoxins are the most toxic chemicals known in nature. They are stable to heat and cannot be broken down by cooking or baking.