How to Identify and Get Rid of Thrips on Houseplants: A Complete Guide

Understanding the Pest

Thrips are tiny, winged insects that are infamous in the plant community. Unlike pests that simply pierce and suck, thrips have “rasping-sucking” mouthparts. They use them to slash and scrape open plant cells before feasting on the contents. This feeding method is what causes the unique silvery, almost shimmery damage.

The biggest challenge with thrips is their life cycle. Adults lay eggs inside the plant tissue. The eggs hatch into larvae that feed on the leaves. When they are ready to pupate, they drop off the plant and burrow into the soil. They later emerge from the soil as adults, fly back up to the leaves, and start the cycle all over again.

How to Identify Thrips: Signs & Symptoms

You need to look for both the pest and the specific damage it leaves behind.

• Silvery Leaf Damage: This is the most telling sign. You will see silvery-white or translucent patches on the leaves where the thrips have fed. The damage can look stippled or streaky and often has a metallic sheen.
• Tiny Black Specks: Within the silvery patches, you’ll see tiny black dots. This is their frass (droppings) and is a key diagnostic clue.
• Visible Insects:
  • Adults: Are very small (1-2mm), slender, and typically black or dark brown. They are fast-moving and may fly or jump when disturbed.
  • Larvae: Are even smaller, pale white or yellowish, and resemble tiny worms. You’ll often find them actively feeding within the damaged areas.
• Deformed New Growth: Thrips love to feed on tender new leaves, causing them to emerge twisted, deformed, or scarred.

How Did They Get In?

Thrips are insidious and can enter your home in several ways.

• New Plants: The number one culprit is an infested plant brought home from a nursery or store.
• Open Windows & Doors: Adult thrips can fly and are small enough to pass through window screens.
• Cut Flowers: Fresh bouquets from a garden can carry thrips indoors.
• On Your Clothing: They can even hitch a ride inside on your clothes after you’ve been outdoors.

Step 1: Isolate the Plant IMMEDIATELY

Step 2: Manual Removal & Rinsing

• Rinse the Plant: Take the plant to a shower or sink and use a strong jet of lukewarm water to dislodge as many adults and larvae as possible. Focus on the undersides of leaves and new growth.
• Prune Heavy Damage: If some leaves are severely damaged, it’s best to prune them off, seal them in a plastic bag, and dispose of them immediately.

Step 3: Treat the Foliage (Adults & Larvae)

Spraying the leaves targets the feeding stages. Repeat this every 3-5 days for several weeks.

• Insecticidal Soap: This is a good first-line defense. It must make direct contact to be effective. Spray the entire plant thoroughly, paying close attention to all the nooks and crannies.
• Spinosad Products: For a stronger (but still organic) option, products containing Spinosad are highly effective against thrips. It works on contact and is also ingested by the pests as they feed. This is often the preferred treatment for serious infestations.

Step 4: Treat the Soil (The Pupae)

This step is crucial to breaking the life cycle and is often missed.

• Systemic Granules: Applying a systemic insecticide to the soil is a very effective method. The plant absorbs the insecticide, making its tissue poisonous to any thrips that feed on it. This kills new larvae and any adults that survive the sprays. Use with caution and follow all label directions.
• Beneficial Nematodes: For a biological approach, you can drench the soil with beneficial nematodes (specifically Steinernema feltiae). These microscopic worms hunt down and kill thrips pupae in the soil.

Proactive Plant Care

• Quarantine New Plants: Keep all new plants isolated for at least a month. Inspect them meticulously and regularly during this period.
• Use Sticky Traps: Thrips are attracted to the colors blue and yellow. Placing blue (or yellow) sticky traps near your plants can help you monitor for and catch adult thrips early.
• Regular Leaf Cleaning: Routinely wiping down the leaves of your plants with a damp cloth can remove eggs and disrupt the life cycle of many pests, including thrips.

Which Plants are Most Susceptible?

Can thrips fly?

Are thrips harmful to humans?

Why are thrips so hard to get rid of?