It doesn't require a green thumb to keep your houseplants healthy. If you can recognize early signs of trouble, you can intervene before problems escalate. Start by knowing what a healthy houseplant looks like: strong, sturdy stems that have non-wilted, evenly colored leaves with a consistent shape. If you see anything different or unusual, take a closer look.
In a home environment, which is often warm, dry and has inconsistent light, insect pests can multiply rapidly on weakened houseplants. There is also a lack of natural predators to keep pest insects in check. It’s a good idea to check your houseplants for insects frequently, maybe once a week or every time you water. However, keep in mind that symptoms common houseplant diseases, improper cultural practices and tough indoors growing conditions can look a lot like pest problems. So make sure you understand all the aspects of properly caring for houseplants and know all the things that can make good plants go bad.
What to Look For
Changes in leaf color or texture is often a sign of an insect problem. Keep an eye out for spotted or speckled leaves, or a general yellowing. Leaves should be brightly colored and not wilted. Also look for distorted or misshapen leaves, or ones that are cupped or pinched, especially on branch tips where there is new growth. Watch out for fine webbing on leaf undersides or where leaves attach to stems.
Some insects, such as Scale and Whiteflies, secrete a sweet substance called honeydew, which can coat leaves, making them unusually shiny and sticky. Sooty mold can then grow in the honeydew, turning the foliage black and sticky. Honeydew can also drip onto nearby surfaces, coating them with a sticky layer.
When looking for insects, give the entire plant the once over. Check beneath leaves, along new growth and where stems and leaves join. A 10-power magnifying glass can help you get a clearer look confirmed diagnosis.
Which Insect Is it?
Over time, you’ll get to know symptoms that indicate the infestation of specific insects. Use this basic guide to identify your invader.
Aphid: Small green, yellow, black or white soft-bodied insects that love to feed on new growth, turning it yellow or distorted. Aphids also produce honeydew and reproduce quickly, often heavily infesting a plant in just a few days.
Spider Mite: Very tiny (not even pinhead-size) spider-like creatures that thrive in hot, dry, dusty conditions. They usually cluster on the undersides of leaves or where leaves join stems. Feeding produces a light speckling or silvery sheen on leaf surfaces, causing plants to look faded or dry. Like spiders they create webbing, which in heavy infestations is one of the most easily detectible symptoms, especially on the undersides of the leaves. Difficult to control but keeping plants clean helps a lot.
Mealybug: Small, cotton-like insects are easily visible, usually between leaves and stems, along stems or under leaves. Mealybugs produce honeydew, distort new growth and generally weaken plants. Isolate infested plants to prevent the pest from spreading.
Scale: Mostly stationary, sucking insects, often with shell-like coverings. Appearance can vary depending on type, but they typically gather on stems and leaf undersides. They can also occur on upper leaf surfaces. Feeding produces distorted growth, honeydew, yellowing, and dropping leaves. Hard to control and can quickly kill plants.
Whitefly: Look like tiny white Moths and often flutter around in clouds when infested plants are disturbed. They usually feed on leaf undersides, often produce a lot of honeydew and resulting sooty mold. Plant growth is stunted; leaves slowly turn yellow and die.
Avoiding Insect Problems
Here are a few simple steps to help minimize insect problems on your houseplants:
- Inspect plants often; once a week or every time you water.
- Clean plant leaves regularly; dust can harbor adult insects, larvae or eggs. For more information on how to clean houseplant leaves
- Provide ideal growing conditions with proper light, water and fertilizer. Nothing keeps insect pests at bay like a healthy houseplant. For more information, see How to Grow Healthy Houseplants