Keeping houseplants healthy doesn’t require a green thumb. If you know what to look for, you can spot early signs of trouble and intervene before problems escalate. Start by knowing what a healthy houseplant looks like: strong stems that have non-wilted, nicely colored leaves with a consistent shape. If you notice a plant veering away from this appearance, inspect further.
In a home environment, houseplant insects multiply rapidly due to a lack of natural predators to keep insects in check. At least weekly, inspect plants for signs of insects.
Insect Calling Cards
Changes in leaf color or texture can signal an insect problem. Leaves may become spotted, speckled or yellowed when insects are present. Leaves might also become distorted or misshapen, often looking cupped or pinched. You may spot webbing draped along leaf undersides or where leaves attach to stems.
Some insects secrete a substance called honeydew, which makes leaves unusually shiny and sticky. Honeydew also encourages sooty mold to grow on leaves, creating black smudges. Often honeydew drips onto nearby surfaces, coating them with a sticky layer.
Look for insects lurking beneath leaves, clustered along new growth or boldly lodged where stems and leaves join. A 10-power magnifying glass can help shift suspicions into a confirmed diagnosis.
Which Insect Is the Culprit?
Certain symptoms indicate the arrival of specific insects. Use this guide to track down your invader.
Aphid: Small green, yellow, black or white soft-bodied insects. Feeding produces honeydew and yellow and/or distorted leaves. Aphids reproduce quickly and can heavily infest a plant in a few days. Look for aphids on new growth.
Spider mite: Very tiny (not even pinhead-size) creatures thrive in hot, dry conditions. Cluster along leaf undersides or where leaves join stems. Feeding produces speckling on leaf surfaces, causing plants to look faded. Webbing occurs with heavy infestations and is likely the most easily detectible symptom. Hard to eradicate.
Mealybug: Small, cotton-like insects are easily visible, occurring most often on stems or leaf undersides. Feeding produces honeydew and distorted growth. Hard to control when numbers are high. Isolate infested plants to limit insect spread.
Scale: Stationary, sucking insects with shell-like coverings that typically gather on stems and leaf undersides, but can occur on leaf surfaces. Feeding produces distorted growth and honeydew. Hard to control.
Whitefly: These insects resemble tiny white moths and flutter around when infested plants are disturbed. Feed on leaf undersides, producing honeydew. Overall plant growth is stunted; leaves turn yellow and die.
How To Avoid Insect Problems
Minimize insect infestations by following a few simple steps.
- Visually inspect plants each time you water.
- Clean plant leaves regularly; dust can shelter insects or eggs. Don’t use a feather duster – it easily spreads insects or eggs. Wipe leaves with a damp sponge or spray plants with water.
- Provide ideal growing conditions. Nothing keeps insects at bay like a healthy plant.
Image 1626007: John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org
Image 2187061: Joseph LaForest, University of Georgia, Bugwood.org
Image 1192033: Sally Tucker, Bugwood.org
Image 5114037: Raymond Gill, California Department of Food and Agriculture, Bugwood.org
Image 1435127: Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org