Many homeowners are dismayed to find tiny white bugs inside their home. Most indoor insects are not harmful or poisonous pests, but they can become a nuisance if infestations are heavy. Properly identifying the bugs inside your home is key to reducing infestations and preventing damage to your home and houseplants.
Tiny white bugs in the potting soil of your houseplants are the larvae of fungus gnats. Adult fungus gnats are delicate, black flies that may swarm if the infested houseplant is moved. The larvae of the fungus gnat is a tiny white grub that lives in the top 2 inches of potting soil. Fungus-gnat larvae feed on organic matter in potting soil, such as algae and fungi. This insect does not cause serious damage to houseplants but is often a nuisance when large numbers of adult gnats swarm indoors. Springtails are another nuisance pest and are wingless insects white or grey in colour and one-tenth of an inch long. These pests also live in organic matter in potting soil but may crawl out and venture into other parts of the house.
Fungus gnats feed on plant roots of infested houseplants but do not usually damage the health and vigour of the plant. These insects do not bite but often swarm near windows because they are attracted to light. Fungus gnats have a short lifespan and reproduce rapidly. Springtails feed on living houseplant tissue and are highly mobile, often crawling around the house. These white bugs are often present in large numbers and are difficult to control.
Over-watering your houseplants is a common cause of fungus-gnat development. Fungus gnats are attracted to wet soil and reproduce rapidly in these conditions. Using sterile potting soil is one way to eliminate fungus gnats in your houseplants. Repotting plants every few months will also help reduce fungus-gnat infestations. Allowing potting soil to dry completely before adding more water will also help discourage fungus gnats. Heavy infestations of springtails almost always require insecticides.
Tiny white fungus-gnat larvae are not eliminated by many insecticides, so control is most effective if aimed at adult flies. Insecticides containing the active ingredients bifenthrin and permethrin may help control adult fungus gnats. If you control the adult gnats, they will lay eggs in the potting soil of your houseplants. Fungus-gnat larvae are sometimes susceptible to applications of imacloprid when applied to houseplant soil. Springtails are often controlled with applications of diazinon applied to the soil and on the outside of pots in the home.