Thrips on Houseplants: How to Identify Them and Get Rid of Them

If your monstera or pothos suddenly has dull, silvery streaks with tiny black dots, you are probably dealing with thrips. They are one of the most frustrating houseplant pests: tiny, fast-breeding, able to fly to the next plant, and hidden for part of their life cycle where sprays can’t reach.

The good news is that thrips are manageable once you understand how they develop. This guide follows integrated pest management (IPM): confirm the pest, combine physical and biological controls, and use pesticides only when you actually need them.

How to identify thrips

Adult thrips are slender insects less than 1/20 inch long. Depending on the species and life stage, they range from translucent white to dark brown, and adults have distinctive fringed wings (UC IPM).

Most people see the damage before they see the insects:

• Silvery patches. Leaves first turn dull green, then develop a silvery-white discoloration on the upper surface (RHS).
• Black specks. Tiny dark dots inside those patches are thrips excrement.
• Distorted new growth. When thrips feed on developing tissue, new leaves can come out twisted, and flower buds may fail to open.
• Scabby, brown discoloration on leaves and petals with heavier feeding (UC IPM).

The white paper test

Hold a sheet of white paper under a leaf and tap the leaf sharply. Thrips fall onto the paper and show up as tiny moving slivers. UC IPM recommends this method, and it is also the easiest way to check whether your treatment is working.

Where to look

Focus your inspection on:

• the youngest leaves and unfurling shoots, where tissue is soft and distortion is most obvious,
• the undersides of leaves along the midrib,
• flowers and buds if the plant is blooming (an anthurium or peace lily, for example),
• the soil surface and saucer, where leaf litter collects.

A 10x hand lens and a flashlight held at a low angle help a lot. Silvery patches shine in raking light, and the black specks stand out. If you find old damage but no insects, watch the new leaves: if they emerge clean, the thrips may already be gone.

Why thrips keep coming back: the life cycle

This is the part that makes or breaks your treatment plan. According to UC IPM, thrips go through these stages:

Stage	Where it lives	What reaches it
Egg	inserted into leaf or bud tissue	nothing from outside; wait for hatching
Larva (2 stages)	on leaves, feeding	rinsing, sprays, predatory mites
Prepupa and pupa	usually in soil or leaf litter, not feeding	cleanup, soil-dwelling biocontrols
Adult	on leaves, flying	sticky traps, sprays, rinsing

In warm conditions, the full cycle takes about two weeks (UC IPM); the RHS gives 24 to 35 days under ideal conditions. Indoors, thrips can breed year-round because the temperature never drops enough to stop them.

The takeaway: one treatment is never enough. Eggs in leaves and pupae in the soil survive, and a new generation shows up a few days later. Plan on several weeks of repeated treatments and checks.

Step 1: Isolate and inspect neighbors

Move the infested plant away from the rest of your collection right away. The RHS advises separating plants with sap-feeding pests from unaffected houseplants to limit spread. Then check nearby plants: both leaf surfaces, leaf axils, and new growth.

Quarantine new plants before they join your collection. Clemson HGIC recommends isolating new plants for six weeks and inspecting them weekly with magnification.

Step 2: Physical control

• Rinse the foliage with lukewarm water, including leaf undersides. Clemson HGIC lists rinsing leaves as a first step against thrips. Cover the soil so you don’t waterlog it.
• Remove badly damaged leaves and flowers, as UC IPM recommends. Bag the debris before throwing it out.
• Clean up leaf litter from the soil surface and saucer, since pupae may be there.
• Hang sticky traps. UC IPM recommends bright yellow; the RHS mentions blue for indoor and greenhouse use. Traps catch flying adults and, more importantly, show you whether the population is shrinking.

Step 3: Biological control

Indoors or in a sunroom, you can release natural enemies. For greenhouses, the RHS lists the predatory bug Orius laevigatus, predatory mites (Amblyseius species), soil-dwelling mites (Hypoaspis species and Macrocheles robustulus), and a nematode product. UC IPM also mentions Euseius predatory mites, green lacewings, and parasitic wasps.

Keep in mind:

• Biocontrols work best as prevention or on light infestations. On a heavily infested plant, combine them with rinsing.
• Predators are sensitive to pesticides. The RHS notes that all biological controls are susceptible to pesticides. If you release predators, skip sprays or confirm the product is compatible.
• Soil predators and nematodes target the stages in the potting mix, while leaf-dwelling mites go after larvae on the foliage. Using both covers more of the life cycle.

Predatory mites and nematodes are sold by specialist biocontrol suppliers. Follow their release instructions and temperature requirements.

Step 4: Sprays when nothing else is enough

UC IPM lists horticultural oils, insecticidal soaps, and pyrethrins as contact options that give temporary control. They only kill thrips they hit directly, so repeat applications are part of the plan. The RHS suggests plant oils and pyrethrum-based products as a first resort.

Spinosad is more effective, according to UC IPM, but it is toxic to some beneficials, including predatory mites, and to bees. Systemic insecticides move into plant tissue where contact sprays can’t reach; Clemson HGIC mentions them for thrips hiding in flower buds, but the RHS describes systemics such as neonicotinoids as the most environmentally damaging option.

Ground rules for any pesticide:

• Use only products registered in your state or country and labeled for houseplants or indoor ornamentals.
• Take the rate, repeat interval, and safety precautions from the label only. The label overrides any advice you read online, including this article.
• Test on a single leaf first and wait a day or two to check for leaf burn.
• Cover leaf undersides. Contact sprays only work on insects they touch.
• Spray away from kids and pets, ideally outdoors or on a balcony.

A multi-week plan

When	What to do
Day 0	isolate, rinse, remove damaged leaves, hang a sticky trap
Days 1–3	release predators or apply the first spray per the label
Weekly	white paper test, check the trap and new leaves
Throughout	repeat treatment per the label or supplier instructions
Finish	return the plant only after several consecutive checks with no thrips

Old silvery patches won’t disappear; damaged tissue doesn’t recover. You’ll know you’ve won when new leaves come in clean.

Common mistakes

• One spray and done. Eggs and pupae survive, and the infestation rebounds.
• Treating only one plant. Adults fly, so neighbors are often infested before it shows.
• Mixing predators and pesticides. A spray can wipe out the predatory mites you just paid for.
• Returning the plant too soon. Wait for several clean checks in a row.

Prevention

• Quarantine new plants and inspect them before buying. Pests usually arrive on new plants (RHS). See our guide to buying rare houseplants for what to check.
• Check leaf undersides regularly, for example every time you water.
• Remove dead leaves from the soil surface.
• Don’t overdo it. UC IPM lists avoiding excess nitrogen fertilizer and overwatering among its cultural controls.
• Keep a sticky trap near plants that have had thrips before.

Thrips or something else?

Fine pale stippling on the upper leaf surface with webbing underneath points to spider mites. White cottony clusters in leaf axils suggest mealybugs. And if leaves are yellowing or browning with no insects in sight, work through our yellow and brown leaves diagnostic guide.