Several types of tiny bugs may find their way into your home when you buy commercial potting soil or new houseplants. The problem is that most of them are too small to see until their population grows.
Some of the most common bugs found in potting soil are aphids, mealy bugs, fungus gnats and spider mites.
Mealy bugs look like small white cotton balls and can produce hundreds of eggs within weeks. Spider mites damage leaves by feeding on their cells, eventually causing leaf drop. Fungus gnats are mosquito-like insects that often carry viruses that can spread to other plants. Aphids tend to feed on the undersides of leaves and secrete honeydew, which can lead to sooty mould.
Check the label to be sure that you are buying sterilised potting soil. You can also sterilise your soil by baking it in an oven at 95 degrees C (200F) for 30 minutes. The heat will kill any pests or eggs living in the soil. Isolate new plants from your existing houseplants until you're sure the soil is insect-free. If the infestation isn't too severe, some tiny bugs may simply be washed or picked off. Otherwise, you'll need a pesticide to prevent widespread infestation.