What causes mealy bugs on house plants that are isolated from other plants?

Pre-infestation is what causes mealy bugs on houseplants that are isolated from other plants. The pests in question may be hiding in soils which have infrequent re-potting schedules or low sanitation levels. They also may be hiding in cracks, crevices, fissures or infrequented spaces before the plant's arrival since only the first two of five instars require food sources.