YEAR-ROUND
Citrus mealybug
White, waxy colonies in the leaf joints and under the leaves; sticky honeydew below.
Crop hub · Indoors · Home garden
Monstera & aroids
The thrips the RHS names on monstera is banded palm thrips (Parthenothrips dracaenae). The RHS says it occurs all year round on houseplants with relatively tough leaves, and names Ficus, Dracaena, Citrus, Monstera, Schefflera and palms. Thrips feeding turns leaves dull or silvery, and the RHS warns that the leaves do not regain their green colour even after the thrips have gone. See thrips on monstera for control, and the thrips group page for how to tell the species apart.
UC IPM lists philodendron among the houseplants that often carry mealybugs. For the related aroids, Clemson lists spider mites and mealybugs on pothos, aphids, mealybugs and spider mites on arrowhead vine, and mealybugs, aphids, scales and mites on Chinese evergreen. Springtails and soil mites in the compost are harmless.
crop context · monstera leaf, underside
The pests on monstera and aroids
YEAR-ROUND
Longtailed mealybug
Long tail filaments and no egg sacs. UConn says many tropical foliage plants are susceptible.
YEAR-ROUND
Brown soft scale
Flat brown bumps on stems and midribs, with sticky honeydew and black sooty mould on the leaves below.
DRY INDOOR AIR
Two-spotted spider mite
Pale speckling on the upper leaf that fades, then bronzes; worst on plants kept indoors all year. Hose or sponge the undersides first.
WET COMPOST
Springtails
Tiny jumping decomposers in the compost. Harmless; they mean it is staying wet.
ReleaseNothing to releaseLet the compost dry between waterings
IN THE COMPOST
Soil mites
Tiny decomposer mites in the potting mix. Not spider mites and not a pest.
ReleaseNothing to releaseNo treatment needed
YEAR-ROUND
Banded palm thrips
Dull, silvery leaves with dark varnish-like specks, worst underneath. The silvering never greens up again.
Season calendar
INDOORS · NORTHERN HEMISPHERE HOMES · QUALITATIVE| J | F | M | A | M | J | J | A | S | O | N | D | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Banded palm thrips (all year) | Jan: Pest pressure high | Feb: Pest pressure high | Mar: Pest pressure high | Apr: Pest pressure high | May: Pest pressure high | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Pest pressure high | Oct: Pest pressure high | Nov: Pest pressure high | Dec: Pest pressure high |
| Mealybugs & scale (breed all year) | Jan: Pest pressure high | Feb: Pest pressure high | Mar: Pest pressure high | Apr: Pest pressure high | May: Pest pressure high | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Pest pressure high | Oct: Pest pressure high | Nov: Pest pressure high | Dec: Pest pressure high |
| Pests carried in on plants from outdoors | Jan: Quiet | Feb: Quiet | Mar: Quiet | Apr: Quiet | May: Quiet | Jun: Quiet | Jul: Quiet | Aug: Quiet | Sep: Pest pressure high | Oct: Pest pressure high | Nov: Quiet | Dec: Quiet |
| Release window | Jan: Quiet | Feb: Quiet | Mar: Quiet | Apr: Quiet | May: Release window | Jun: Release window | Jul: Release window | Aug: Release window | Sep: Release window | Oct: Quiet | Nov: Quiet | Dec: Quiet |
- Pest pressure high
- Building
- Release window
- Quiet
- Banded palm thrips (all year) · high pressure Jan–Dec
- Mealybugs & scale (breed all year) · high pressure Jan–Dec
- Pests carried in on plants from outdoors · high pressure Sep–Oct
- Release window · release May–Sep
Starter program
A big monstera is one plant with a lot of leaf, so most control is hands-on: rinse, wipe and check the undersides. We found no release trial against banded palm thrips, so the predator rate shown for it above is UC IPM's western flower thrips rate, not a tested one.
- ON BUYINGQuarantineKeep a new plant apart from the others for six weeks and check the leaf undersides weekly with a 10x lens.
- SILVERY LEAVESRinse, soap and blue sticky cardsRinse the leaves with water and spray insecticidal soap (Clemson). Blue sticky cards among the plants catch thrips and show whether numbers are falling (RHS).
- FIRST MEALYBUGSCryptolaemus montrouzieri5 beetles per infested plant, onto a colony with egg sacs, above 61 °F (16 °C). Dab small colonies with rubbing alcohol diluted to 70% or less instead, testing it on one leaf a day or two first (UC IPM).
- LIVE SCALE, CRAWLERSRhyzobius lophanthae2–5 per infested plant every 1–2 weeks. Rinse off honeydew first. Scrape off early scale with a fingernail.
Setting up indoors
Clemson's routine for smooth-leaved houseplants suits monstera's big leaves.
Wipe the leaves every 2–3 weeks
Clemson says washing smooth-leaved plants every two to three weeks discourages pest infestations. Do both sides of the leaf.
Spray water hard on the undersides for spider mites
A forceful spray dislodges mites and breaks up webbing. Clemson notes it usually has to be repeated weekly for several weeks.
Separate an infested plant
The RHS advises moving plants with sap feeders away from the others to limit spread, and increasing ventilation to check sooty mould.
Do not expect silvered leaves to recover
Thrips-damaged leaves stay pale after the thrips are gone. Judge progress by the new leaves.