What Are the Tiny Bugs Living in My Potting Soil?

Aphids, pictured crawling on milkweed, are sometimes present in potting soil.

There are several types of tiny bugs that 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.

Types

Some of the most common types of bugs found in potting soil are aphids, mealy bugs, fungus gnats and spider mites.

Features

Mealy bugs look like small white cotton balls and can produce hundreds of eggs within weeks. Spider mites produce webs and 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 are winged insects that tend to feed on the undersides of leaves and secrete honeydew, which can lead to sooty mold.

Solution

Check the label to be sure that you are buying sterilized potting soil. You can also sterilize your soil by baking it in an oven set at 200 degrees 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 off or picked off. Otherwise, you'll need a pesticide to prevent widespread infestation.

References

• Colorado State University Extension: Managing Houseplant Pests
• Guide to Care Free Houseplants: Troubleshooting houseplant diseases, problems and pests

Resources

• University of Minnesota Extension: Houseplant Insect Control