Common Houseplant Pests: Identifying and Treating Them

Houseplants are an excellent way to bring life and greenery into your indoor spaces, but they can also attract unwanted pests. Common houseplant pests such as aphids, spider mites, and whiteflies can cause various issues, such as yellowing leaves, stunted growth, and even plant death in severe cases. In order to maintain the health and beauty of your houseplants, it’s crucial to spot the signs of a pest infestation early and use safe, effective methods to eliminate them.

Aphids (Top L), Whiteflies (Top R), and Mealybugs (Bottom)
Pest Description Where to find them
Aphids are small, soft-bodied insects that can be green, yellow, black, or brown. They tend to congregate on new plant growth, sucking the sap from the leaves and stems. Aphids can cause leaves to curl, yellow, or become deformed. They also excrete a sticky substance called honeydew, which can lead to the growth of sooty mold.
Usually found on the underside of leaves, can be green, black, brown, or red.
Mealybugs are small, white, cottony insects that feed on plant sap, leading to weakened plants and distorted growth. They tend to gather in crevices and leaf axils, where they are protected from predators and insecticides. Mealybugs also excrete honeydew, which can lead to sooty mold growth.
Usually found on stems and leaves, can be mistaken for cotton or mold.
Spider Mites
Spider mites are tiny, barely visible pests that feed on plant sap, causing stippling, yellowing, and leaf drop. They thrive in dry, warm conditions and can multiply quickly if left unchecked. A fine webbing may be visible between leaves and stems when infestations become severe.
Usually found on the underside of leaves, can cause webbing to form on the plant.
Fungus Gnats
Fungus gnats are small, black flies that are often found buzzing around houseplants. Their larvae feed on organic matter in the soil, which can cause damage to plant roots. Fungus gnats are particularly attracted to wet, overly moist soil conditions.
Can be seen flying around the plant or in the soil, larvae are small, white, and worm-like.
Scale Insects
Scale insects appear as small, immobile bumps on plant stems and the undersides of leaves. They feed on plant sap and can weaken or kill plants. There are two types of scale, armored and soft. These pests can be difficult to control since their protective covering makes them resistant to many insecticides.
Scale insects can be found on various parts of the plant such as leaves, stems, branches, and fruits.
Whiteflies are tiny, white, winged insects that feed on plant sap, causing yellowing, stunted growth, and leaf drop. They tend to congregate on the undersides of leaves, and a cloud of small, white insects will fly up when an infested plant is disturbed.
Whiteflies are generally found on the undersides of leaves on plants. They are usually found in large numbers.
Thrips are tiny, slender insects that feed on plant sap, causing leaf distortion, stippling, and silvering. They can also transmit plant viruses. Thrips are difficult to see due to their small size and fast movement, but their damage can be quite noticeable on the affected plants.
Thrips can be found on various parts of the plant, including leaves, flowers, and fruits.
A collection of houseplant pests
Fungus gnat (Top L), Thrips (Top R), and Spider mites (Bottom)

Prevention of Common Houseplant Pests

Preventing common houseplant pests is much easier than dealing with an infestation. Here are some tips to keep your plants healthy and pest-free:

  1. Inspect new plants before bringing them home: Always inspect new plants before bringing them home. Look for signs of pests or damage, such as yellowing leaves, webbing, or sticky residue. If you notice any signs of pests, do not bring the plant home.
  2. Quarantine new plants: Before introducing new plants to your existing collection, it’s essential to quarantine them for a couple of weeks. This process helps to identify and treat any potential pests before they have the chance to spread to your other houseplants.
  3. Keep plants clean: Dust and debris can attract pests, so it’s important to keep your plants clean. Wipe down leaves with a damp cloth or sponge to remove dust and debris.
  4. Use clean soil: Always use fresh, clean soil when repotting plants. Avoid using soil from your garden, as it may contain pests or disease.
  5. Avoid overwatering: Houseplants require different amounts of water and nutrients to stay healthy. Overwatering and underwatering can both stress plants, leading to root rot, which can attract pests. Make sure to only water your plants when the soil is dry to the touch.
  6. Provide proper air circulation: Good air circulation can help prevent pests from taking hold. Make sure your plants are not crowded together and that there is space between them.
  7. Climate control: Providing an optimal environment for your houseplants is essential for their overall health and resilience against pests. This includes maintaining appropriate temperature, humidity, and light levels. Maintaining a stable environment can help prevent pest infestations by minimizing plant stress

Treatment of Common Houseplant Pests

Mechanical Control

Mechanical control involves physically removing the pests from the plant. This method is effective for larger pests like slugs and snails, which can be removed by hand. For smaller pests like spider mites, a forceful spray of water can knock them off the plant. Sticky traps can also be used to catch flying insects like fungus gnats.

Here are some mechanical control methods:

  • Handpicking larger pests like slugs and snails
  • Forceful spray of water to remove smaller pests like spider mites
  • Sticky traps to catch flying insects like fungus gnats

Biological Control

Biological control involves using natural predators to control the pest population. This method is effective for pests like mealybugs and scale insects, which have natural predators like ladybugs and lacewings.

Some biological control methods include:

  • Introducing natural predators like ladybugs and lacewings to control mealybugs and scale insects
  • Using nematodes to control soil-dwelling pests like fungus gnats
A ladybug eating aphids and whiteflies from a plant stem

Chemical Control

Chemical control involves using insecticides to kill pests. This method should be used as a last resort, as it can harm beneficial insects and potentially pollute the environment. When using insecticides, be sure to follow the instructions carefully and use them sparingly!

Here are some chemical control methods:

  • Insecticidal soap to control soft-bodied pests like aphids and spider mites
  • Neem oil to control a wide range of pests
  • Systemic insecticides to control pests from the inside out
Neem oil for plant pest control
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