This article was originally published on February 3, 2018 and expired on February 10, 2018. It is provided here for archival purposes and may contain dated information.
I have had houseplants since I was a young girl. Over the years, I have learned so much about caring for them. Most thrive, but I have had failures. One of my biggest concerns is insects, because they are very hard to control. Some eat the plant leaves, while others suck juices from the plants. Let us look at a few of the sucking insects.
Sucking insects suck the plant’s sugary sap, causing the leaves to turn yellow. Since these insects cannot fully digest all the sugar, they secrete a sticky substance called honeydew. Examples include scale, mealybugs, and aphids. Houseplants infected with these insects will have sticky leaves on surfaces below.
Scale insects are hard to see. They are brown or gray in color and extremely small. To the untrained eye, they might look like part of the plant. Upon closer examination, these are round, oval, or shell-shaped shells located on branches and stems of infected houseplants. The scales can easily be scraped off the stem. The insects live under the protective scale, which makes control difficult.
Scale insects have three stages of growth: egg, crawler, and adult. They are easiest controlled during the crawler stage when they move across the plant looking for feeding location. Eventually crawlers settle down and transform into the adult stage. At this stage, they lose all their appendages and secrete a waxy covering to form the “shells” which protect the pests.
Mealybugs are more obvious. They appear as small, white cottony balls that cluster at the base of leaves. Since they are small, mealybugs hide at the base of leaves and make control difficult.
Aphids are not as common indoors but do occasionally occur. These also are very small. Aphids are an eighth-inch long and come in many different colors: green, pink, red, yellow, brown, or black. In the right situation, aphids build in large numbers, clustering upon new growth and stems.
For all three of these insects, begin by grooming and cleaning the plant. If possible, prune off damaged plant parts or areas with heavy pest numbers. Cleaning should remove a few insects. Options vary by plant. Strong water sprays in a sink or bathtub work for some. Others need a more through soap and water cleaning. I use 1-2 tablespoons gentle dishwater soap per gallon of water and hand wipe the top and bottom of each leaf. In some cases, I thoroughly spray the soap solution on plants using a small spray bottle. Clean hairy leaved plants, such as African violets, with a gentle brush.
There are very few insecticides labeled for use indoors to control houseplant insects. Insecticidal soaps are sometimes an option. Follow all label directions carefully; making sure the product is labeled for indoor homeowner use to control the intended insect on the specific plant type. Repeated applications are often necessary to control missed insects or ones that hatch later.
Be sure to isolate infested plants to prevent insects from spreading to other plants. I learned this the hard way many years ago when I lost all my African violets to mealy bugs. Today, I’ll throw the plant away, after saving a few pest free leaves to propagate new plants.
For more information, go to the University of Illinois Extension website on houseplants at http://extension.illinois.edu/houseplants.
Source: Rhonda J. Ferree, Extension Educator, Horticulture, email@example.com
Pull date: February 10, 2018