1. Pests in withered, dry plants:
Dry plants are mainly infested by drugstore beetles and cigarette beetles and their close relatives, the spider beetles. It is likely that they in nature live closely by bird nests and other animals, where they feed on spilled feed and plant tissue that the nests are made of. What makes them interesting as food pests is their ability to tolerate much of the natural toxins in plant tissue. They have a special fondness for spices (pepper, saffron, nutmeg, cinnamon, vanilla etc). Some species feed on tobacco and you can also expect to find them in dry soup vegetables, soup powder, dried flowers and leaves used for tea or herbal substances. It is not important what form these herbal substances take. The pests can find them even if they are included in tablets and lozenges.
2. Pests in mouldy plant tissue:
Dead, moist plant tissue in our latitudes is degraded by fungus. Flour mites, sugar mites, house mites, booklice and plaster beetles graze on these fungi, whether they grow on food, packaging or on the walls of the premises. Brown house moth larvae can only develop in goods which are in moisture equilibrium with 80% RH or more. Therefore it is assumed that micro-fungi are also a necessary part of their diet.
3. Pests in decaying and fermenting plant tissue:
The prune mite feeds on bacterial decomposition of sugar in fruit and can be found in dried fruit when the water content is too high. The house fly and the lesser house fly can develop in fermenting and rotting accumulations of plant tissue. In the case of livestock these breeding sites are replaced by animal manure that also contains amounts of plant tissue degradation. Fruit flies belong to the same niche. They lay their eggs in fermented fruits or products with similar qualities (fruit juice, ketchup, beer, etc.).