This is the time of year your house plants might get the blues. What’s happening is they may be losing leaves or not looking as nice and shiny green as they once did.
There are a few different types of insect pests that could be causing some of these problems. One of the most common house plant pests is fungus gnats. These are tiny dark flies that you’ll see moving around the plants in the area where they are are infested.
However, it’s really the larvae that’s causing the problem. They feed on the roots. They love moist organic matter, so moist soil. So the best way to manage fungus gnats is to reduce the amount of water you add to the pots. You want your pots to dry out thoroughly between each watering. If the problem persists you can repot your plants with sterile new soil. Also you can add a layer of sand or gravel to the surface of the soil in the pot to reduce their activity. You can use a biological insecticide that contains BT, a common brand name is Gnatrol, and you apply this as a drench to the pots.
Another type of common pest are scale and mealybugs. These will be seen on the surface of the leaves. Scale and mealybugs as well as aphids cause a sticky honeydew that drips from the leaves. You can use a diluted alcohol solution of 25% concentration and rub it on the leaves with a cotton ball or other soft cloth. You can also use insecticidal soap, horticultural oils or you can use an insecticide drench that’s registered to use on indoor plants such as imidacloprid.
So the most important things are good lighting, regular watering but not too much, and good drainage in your pots and you should avoid many of the house plant blues.