Tiny black flying bugs


Hello: Our house is filled with tiny black flying bugs, which fly not just around the plants, but throughout the house; they are attracted to light. In the summer, I put most of my houseplants outside, and bring them inside in September. There are 8 plants, including an 8 ft ficus benjamina and a large 30 year old monstera deliciosa (great name!) Before bringing them in, I spray both the leaves and the soil with insecticidal soap. The two I mention are very large, and I may not have been able to spray all the surfaces. Any thoughts on how I might get rid of them? Thanks very much. Sharron
P.S. tried to photograph some, but they’re too small.


Thank you for contacting the Toronto Master Gardeners.

You are doing the right thing by spraying the plants before bringing them indoors for the winter. As a rule of thumb its a good idea to give your plants a good spray with water then douse plants that have spent the summer outdoors with insecticidal soap before bringing them indoors.The most likely culprits you are seeing are fungus gnats. They are small, slender, dark insects that fly around when plants are disturbed. While the adult flies are annoying it is the larvae which may cause problems. The adults lay their eggs in soil that contains decaying organic material. Larvae, particularly if a large number are found in the soil, may cause root damage or stunted growth.
Proper water management and removal of plant debris will break the life cycle of these pesky gnats and will allow you to continue enjoying your houseplants
Fungus gnats commonly develop in the soil of potted plants when the plant is overwatered. Once you have these pesky little bugs it takes patience to be rid of them. You can try the following:

• Drench potting soil with insecticidal soap being careful to follow the manufacturers instructions.
• Place yellow sticky traps that catch bugs around the plant
• If the numbers are very high, apply beneficial nematodes that will attack the larvae. (Nematodes can be bought commercially at reputable garden centres)
• Repot the plant using a sterile potting mix containing minimal organic matter
Let your soil dry out more between waterings as larvae cannot survive in dry soil. Try catching adults by placing yellow sticky traps in the soil. For further information you may wish to read Fungus Gnats

The following information is form one of our aarchived posts. It gives tips on preparing your plants to be brought indoors for the winter
“Not all plants are equal in terms of their requirements. Generally, tropical plants need to be brought back indoors by the first day of autumn or before nighttime temperatures start dropping consistently below 10C. Depending on the size of the pot, there are several steps you may want to follow:
• Inspect your Tropicals for insects and any diseases. Look under their leaves and around the stems. If diseased, treat according to the disease before bringing indoors as you want to avoid infecting your other plants. If you find insects, you can remove them or hose off your plant, knocking off any crawling insects.
• If the pot is small enough to handle, you can soak it for 15 minutes in lukewarm water to force any insects out of the soil. If you find many insects in the soil, you may want to consider repotting. Always use a fresh bag of potting soil mix to replant.
• You can spray your plants with a gentle mix of insecticidal soap and water (follow the manufacturer’s instructions).
• You may also do a light pruning at this time. Cut back about a third of the plant’s overall growth to improve its shape, and remove any leggy, weak growth and dead or diseased stems.
• Place the plants indoor in similar light conditions as they were outdoor (i.e. if they were in direct light outside, place them in a south window indoors). When plants are brought indoor they need to re-adapt and the goal is to prevent them from going into shock. They will naturally lose some leaves as they become accustomed to their new environment but you soon should see new leaves forming.
• Humidity, light and even air, are quite different indoors than outdoors; therefore, get your plant acclimatized gradually. Do not overwater as evaporation rates indoors are different and it takes plants a bit longer to dry out at this time of the year when the furnace is not yet on.
• Only water when the soil is dry. As the fall turns into winter, reduce your watering frequency, and from October to March use little or no ( 20-20-20) fertilizer.
It will take a few weeks for your plants to adapt to their new environment. Do not expect a great amount of growth as the low humidity and low light do not stimulate rapid growth. You will start seeing some changes early next spring as the daylight hours and light levels increase.
If you have further questions about the requirements for each of the plants, do not hesitate to let us know what they are and we will be happy to give you more information on their specific care.
You may wish to refer to our Gardening Guide: Beginner’s Guide for Growing Houseplants for general information.”